Tests & measurements
Blood tests for brain fog
and what else to measure.
Understand what a test measures, why it may come up, and what question it can help answer. Search by test name, biomarker, symptom or type of check.
Common lookups
Search all 165 explainers or browse the library below.
165 current test explainers Labs · screeners · at-home measures · imaging · specialist checks
Common first lookups
Which tests do people look up first?
Many readers start with these reference pages. They aren't a checklist of tests to order.
01 Ferritin A ferritin blood test estimates stored iron. It can help find low iron stores, but the… Lab 02 Vitamin B12 A total vitamin B12 blood test measures cobalamin circulating in the blood. It can support a… Lab 03 Thyroid Function Tests Thyroid function tests include TSH, free T4, and sometimes T3. Each test answers a different… Lab 04 CBC + CMP Blood Test Bundle CBC + CMP is a bundle of two blood panels. The CBC measures blood cells. The CMP measures 14… Lab 05 HbA1c An HbA1c blood test estimates your average blood sugar over the past 2 to 3 months. It is… Lab 06 Overnight Sleep Study (PSG) An overnight sleep study, also called polysomnography or PSG, records sleep, breathing,… Specialist 07 NASA Lean Test: Instructions and POTS Result Limits A supervised 10-minute standing check. After quiet rest lying flat, it records heart rate,… At-home measure 08 Medication Review A structured check of every prescription, store-bought medicine, supplement, inhaler, patch,… Specialist
I already have a result
Already have a result in your hand?
Go straight to the explainer for that test. Each page covers what the number can and cannot answer, what usually gets checked alongside it, and what to ask next.
01 Ferritin A ferritin blood test estimates stored iron. It can help find low iron stores, but the… Lab 02 CBC with Differential A complete blood count with differential uses one blood sample. It measures red blood cells,… Lab 03 Vitamin B12 A total vitamin B12 blood test measures cobalamin circulating in the blood. It can support a… Lab 04 Folate (Serum or RBC) This blood test usually measures folate in serum, the liquid part of blood. Food and… Lab 05 Thyroid Function Tests Thyroid function tests include TSH, free T4, and sometimes T3. Each test answers a different… Lab 06 HbA1c An HbA1c blood test estimates your average blood sugar over the past 2 to 3 months. It is… Lab 07 Fasting Plasma Glucose Blood Test This lab test measures blood sugar after at least 8 hours with no calories. It can help… Lab 08 Vitamin D Blood Test A vitamin D blood test usually means serum 25-hydroxyvitamin D, often written 25(OH)D or… Lab 09 Brain MRI A brain MRI makes detailed pictures of the brain. It can look for tumors, stroke damage, MS,… Imaging
These pages explain a result you already have. They do not tell you what to order.
Complete library
What does each test check?
Topic is the default view. Filter by test type or switch the same library to Test type or A–Z.
Panels & bundles
1 explainer
Test What it measures Why it comes up Type & access Range / context
Lab Nutrient Deficiency Blood Test Panel A targeted lab discussion for iron, B12, folate, vitamin D, CBC, and related markers when deficiency is a serious clue, not a one-size-fits-all nutrient… People often consider a broad vitamin panel because they feel worn out, muddled, weak, lightheaded, numb, or slow. They may not know which nutrient to… Each marker has its own unit, method, interval, and reason for being ordered →
Blood, iron & nutrients
17 explainers
Test What it measures Why it comes up Type & access Range / context
Lab Active B12 (Holotranscobalamin) Active B12 is another name for holotranscobalamin. It measures vitamin B12 attached to transcobalamin, the transport protein that makes this fraction of… Active B12 can be the first test used to check for low vitamin B12. NICE prefers it as the first B12 test during pregnancy. It may help when trouble… Use the active B12 decision bands or the validated interval on the report, plus symptoms… →
Lab CBC with Differential A complete blood count with differential uses one blood sample. It measures red blood cells, white blood cells, platelets, and the main types of white… The panel can find anemia, a change in white cells, a platelet problem, or changes in several kinds of cells. These may matter when trouble thinking… Use each marker's age-, sex-, pregnancy-, and laboratory-specific interval, then compare… →
Lab Ferritin A ferritin blood test estimates stored iron. It can help find low iron stores, but the number can rise with inflammation, infection, liver disease, and… Ferritin may help if you feel tired, exercise feels harder, or your legs feel restless. Heavy periods, pregnancy, recent bleeding, or poor iron absorption… Use the range on the lab report and the reason for testing →
Lab Folate (Serum or RBC) This blood test usually measures folate in serum, the liquid part of blood. Food and vitamins can change serum folate quickly. Some labs test folate in red… Low folate can affect red blood cells and may cause tiredness or trouble focusing. The test may help when there are signs of anemia, a limited diet, heavy… Use the range on the lab report. Keep the test type, recent food or vitamins, and the… →
Lab Glutathione Blood Test (GSH) A glutathione blood test may measure reduced GSH, total glutathione, oxidized GSSG, or a ratio. It may use whole blood, red blood cells, or plasma. The… The name can hide several different tests. You can't compare a reduced-GSH result in mg/dL RBC with total glutathione in µg/mL, a plasma result in nM, or a… Use the range printed by the lab for the exact test, blood sample, method, and unit.… →
Lab Homocysteine A homocysteine blood test measures an amino acid, which is a building block used by the body. Vitamin B12, folate, vitamin B6, and enzymes help process it.… Low B12 or folate can raise homocysteine. So can kidney disease, low thyroid, smoking, age, sex, menopause, medicines, vitamins, and a delay in handling… Use the lab range for the person's age and sex. Read the result with B-vitamin, kidney,… →
Lab MCH Blood Test MCH is a calculated part of a complete blood count, or CBC. It estimates the average amount of hemoglobin in one red blood cell. MCH mostly supports what hemoglobin and MCV already show. Hemoglobin shows whether anemia is present. MCV, RDW, history, and other tests guide the next… Use the MCH interval printed on your CBC report. The laboratory that ran the test sets the… →
Lab MCHC Blood Test MCHC is part of a complete blood count, or CBC. It compares hemoglobin with the space taken up by your red blood cells. MCHC supports the red-cell picture. A low result can fit a small-cell anemia picture. An unexpected high result may need a sample check before looking for… Use the MCHC interval printed on your CBC report. The laboratory that ran the test sets… →
Lab MCV (Mean Corpuscular Volume) Blood Test A calculated part of the complete blood count, or CBC. MCV estimates the average size of your red blood cells. It helps sort anemia into small-cell,… MCV helps choose which cause of anemia to check next. Small cells may point to iron deficiency or an inherited blood condition. Large cells may occur with… Use the age-specific interval printed by the laboratory that performed the CBC. MCV is the… →
Lab MMA (Methylmalonic Acid) A methylmalonic acid (MMA) test measures a substance that can rise when the body cannot use vitamin B12 well. It often follows an unclear total or active… B12 deficiency can cause trouble thinking, numbness, balance problems, and fatigue even without anemia. A high MMA can support the B12 diagnosis. Kidney… Use the reference interval on the serum or urine report with B12, kidney, age, and… →
Lab Neutrophil-to-Lymphocyte Ratio (NLR) NLR is a number from a complete blood count with differential. Divide the absolute neutrophil count by the absolute lymphocyte count. The ratio can add… The ratio can make a shift between two white-cell groups easier to notice, but it can also hide what actually changed. An NLR of 4 could come from higher… There is no universal NLR cutoff for inflammation, brain fog, diagnosis, prognosis, or… →
Lab Omega-6 to Omega-3 Ratio This ratio compares measured omega-6 and omega-3 fatty acids. Some reports divide total omega-6 by total omega-3. Others show an arachidonic-acid-to-EPA… A result such as 8:1 looks simple, but it leaves out the question that changes the meaning: what produced the eight? The ratio can rise because omega-3 is… There is no universal optimal omega-6 to omega-3 blood ratio. The number depends on… →
Lab Platelet-to-Lymphocyte Ratio (PLR) PLR is a number from a CBC with differential. Divide the platelet count by the absolute lymphocyte count. The ratio can add context to a research or… A single ratio can hide two very different blood-count changes. A PLR of 160 could come from more platelets, fewer lymphocytes, or both. More platelets can… There is no universal PLR cutoff for inflammation, stroke risk, brain fog, diagnosis,… →
Lab RBC Magnesium Test A laboratory measurement of total magnesium in separated red blood cells, usually reported in mg/dL or mmol/L. It samples a different blood compartment… Online advice often says serum magnesium is useless and RBC magnesium is more accurate. The evidence is not that simple. Low serum magnesium matters,… Use the performing laboratory's own red-cell magnesium interval, method, specimen… →
Lab TSH, B12 and Ferritin Tests TSH checks thyroid control, vitamin B12 checks B12 status, and ferritin checks stored iron. The three tests can use one blood draw when there is a reason… Thyroid problems, B12 deficiency, and low iron can all cause tiredness and trouble concentrating. They can also affect mood, nerves, exercise, or how hot… Use the result rules for TSH, the type of B12 test, and ferritin separately →
Lab Vitamin B12 A total vitamin B12 blood test measures cobalamin circulating in the blood. It can support a B12 deficiency workup. Read the number with symptoms, risk… Low B12 can affect nerves and thinking even without anemia, but brain fog by itself isn't a strong reason to blame B12. Testing is more useful when another… Use the reporting laboratory interval, symptoms, risk factors, and the type of B12 test →
Lab Vitamin D Blood Test A vitamin D blood test usually means serum 25-hydroxyvitamin D, often written 25(OH)D or 25-OH vitamin D. It estimates vitamin D status from food,… Low 25-OH vitamin D can matter for bone and muscle health, and severe deficiency has clearer medical consequences than a borderline result. Low vitamin D… Use the reporting laboratory interval and the reason for testing. One widely used… →
Thyroid & hormones
20 explainers
Test What it measures Why it comes up Type & access Range / context
Lab 8 AM Cortisol Blood Test An 8 AM cortisol blood test measures total cortisol near the usual morning peak. Clinicians use it as an adrenal screen, often before deciding whether ACTH… Cortisol helps control blood pressure, blood sugar, inflammation, and the body's response to stress. A low level can occur with adrenal or pituitary… Use the lab interval, exact collection time, ACTH if ordered, steroid exposure, estrogen… →
Lab ADH, Copeptin, and Osmolality Review This workup checks how much water is in your blood and urine. It also checks whether your water-control hormones match those results. Too much or too little water can change your sodium level and affect your brain. Ask about this workup if you feel very thirsty, urinate often, wake to… Read the blood and urine results together, including sodium, osmolality, urine specific… →
Lab Cortisol Awakening Response Test The cortisol awakening response, or CAR, is a set of saliva samples. You collect the first sample as soon as you wake and the rest during the next hour.… CAR may help study morning cortisol timing. It is sometimes used when a person wakes tired, crashes in the morning, works nights, or cannot sleep at night.… No universal diagnostic target. Many research descriptions look at the rise across the… →
Lab Cortisol Testing Overview Cortisol can be measured in blood, saliva, urine, and sometimes hair. Each version answers a different question. An 8 AM blood test, ACTH stimulation test,… People often arrive here after fatigue, sudden crashes, steroid use, low blood pressure, online claims, or a private hormone panel. Cortisol may mean a… No single cortisol target. Interpretation depends on sample type, collection time, wake… →
Lab DHEA-S Blood Test This blood test measures DHEA-S, a hormone made mainly by the adrenal glands. Clinicians may use it to check fast hair, skin, voice, or body changes, PCOS,… Normal DHEA-S levels can differ by hundreds of mcg/dL across a lifetime. A result that's normal for a young man may be high for an older woman. A low… Use the range printed by the lab for your age, sex, and test method. DHEA-S changes after… →
Lab Free T3 This blood test measures the small amount of T3 thyroid hormone that is not bound to a protein. Free T3 is usually an extra thyroid test. It is not the… Free T3 may help when TSH is low but free T4 is still in range. It can also show how high thyroid hormone is. It is less useful for finding an underactive… Use the lab range for your age and test method. Read free T3 with TSH and free T4. →
Lab Free T4 This blood test measures the small amount of T4 thyroid hormone that is not bound to a protein. Free T4 can enter body tissues. Read it with TSH. Too little or too much thyroid hormone can affect energy, body temperature, heart rate, sleep, mood, and thinking. Free T4 shows how much hormone is… Use the range on your lab report. Read free T4 with TSH, age, pregnancy, illness,… →
Lab Free Testosterone Blood Test This blood test checks the small amount of testosterone that is not held tightly by a protein called SHBG. The lab may measure it or calculate it. It is… The test method matters. A lab may measure free testosterone by equilibrium dialysis, calculate it from total testosterone and SHBG, or use a less reliable… Use the range printed by the lab for your age, sex, test method, and unit. There is no… →
Lab Hair Cortisol Test This lab test measures cortisol in a cut piece of hair. The 3 cm closest to the scalp is often used to estimate exposure over recent months. Hair grows at… The result is not a direct three-month average of blood cortisol. A high value may come from the body, prescribed hydrocortisone, cortisol cream on the… There is no single cutoff for chronic stress. Use the range printed by the lab for the… →
At-home measure Menstrual Cycle and Symptom Diary A private daily record of bleeding, symptoms, and what they stopped you doing. It can show whether symptoms happen before a period, last all month, or have… It is easy to remember the worst days and forget the easier ones. A short daily entry shows when symptoms start and stop. This helps separate symptoms tied… There is no pass or fail score. Record symptoms daily across at least two cycles when PMDD… →
Lab MSH (Melanocyte-Stimulating Hormone) A specialist frozen-plasma test for alpha-melanocyte-stimulating hormone (alpha-MSH), a small signaling protein. Alpha-MSH helps control skin color and… You may hear that any result below 35 pg/mL proves CIRS or that 60 to 81 pg/mL is an ideal level. Current laboratories do not agree with that range. Before… Use the interval printed by the laboratory that performed the exact alpha-MSH assay.… →
Lab Reverse T3 Reverse T3 is an inactive product made when the body converts thyroxine, or T4, along a different pathway from active T3. It can change during serious… For routine outpatient questions about hypothyroidism or brain fog, use TSH and free T4. Specialists may use reverse T3 in a small set of illness,… Use the reporting laboratory's method-specific interval only in the limited clinical… →
Lab SHBG Blood Test Sex hormone-binding globulin (SHBG) is a liver-made protein that carries testosterone, dihydrotestosterone, and estradiol in blood. The test helps explain… SHBG is often listed beside testosterone because it changes what the hormone result means. When SHBG is low, total testosterone can fall even if the body's… Use the performing laboratory's age-, sex-, life-stage-, and method-specific interval.… →
Lab Testosterone Blood Test A blood test that usually measures total testosterone and may be followed by the unbound fraction, SHBG, or other hormones. It is used for selected… A testosterone report needs the reason for testing. The same value means something different for sexual symptoms, new facial hair and irregular periods,… There is no universal testosterone target. Use the reporting laboratory's age-, sex-,… →
Lab Thyroglobulin Antibodies A thyroglobulin antibody test looks for immune proteins that react to thyroglobulin, a protein made in thyroid cells. The result is also called TgAb or… TgAb can support an autoimmune thyroid explanation when read with TSH, free T4, symptoms, and usually TPO antibodies. After treatment for differentiated… Use the reporting laboratory's assay-specific cutoff with TSH, free T4, and the reason the… →
Lab Thyroid Function Tests Thyroid function tests include TSH, free T4, and sometimes T3. Each test answers a different question, so most people do not need all three ordered at… An underactive or overactive thyroid can affect thinking, energy, mood, sleep, heart rate, temperature tolerance, and bowel habits. Those symptoms also… Use each reporting laboratory interval and interpret the tests in the order they were… →
Lab Total and Free Testosterone Panel A paired blood panel that reports total testosterone plus free or unbound testosterone. The free value may be measured by equilibrium dialysis, calculated… Total testosterone shows bound plus unbound hormone. Free testosterone estimates or measures the small fraction not bound to proteins. Reading both can… There is no universal paired target. Use the laboratory's age-, sex-, method-, unit-, and… →
Lab Total Testosterone Blood Test A serum blood test that measures protein-bound plus unbound testosterone together. It is the usual starting measurement for selected adult male… Total testosterone is more standardized than most free-testosterone methods. Time of day, illness, sleep, medicines, body composition, SHBG, puberty,… Use the reporting laboratory's age-, sex-, method-, unit-, and collection-time-specific… →
Lab TPO Antibodies A TPO antibody blood test measures immune proteins aimed at thyroid peroxidase, an enzyme the thyroid uses to make hormone. It can support an autoimmune… Underactive or overactive thyroid function can affect energy, mood, sleep, heart rate, temperature, and thinking. The antibody test can help explain why… Use the reporting laboratory's assay-specific negative or positive cutoff with TSH and… →
Lab TSH (Thyroid Stimulating Hormone) TSH is a hormone made by the pituitary gland. It controls how much T4 and T3 the thyroid makes. Read the result with the lab range and, when needed, free… An underactive or overactive thyroid can affect thinking, but brain fog by itself doesn't identify a thyroid problem. TSH is more useful when you have… Use the reporting laboratory interval with free T4, age, pregnancy, medicines, and the… →
Blood sugar & metabolism
9 explainers
Test What it measures Why it comes up Type & access Range / context
Lab A1c and Fasting Glucose Review An A1c and fasting glucose review compares a longer-term glucose average with one fasting result. It can help when the numbers look normal but symptoms… A1c shows your average blood sugar over the past few months. Fasting glucose shows your level at one moment before eating. Neither test shows every short… Use ADA diagnostic thresholds, the exact fasting status, symptoms, medication context, and… →
Lab Blood Sugar Assessment A blood sugar assessment uses several tests. It may help when you feel foggy after a meal, wake up shaky, or have symptoms that one A1c or fasting glucose… A1c, fasting glucose, insulin, and home readings show different parts of blood sugar. Read them with meals, symptoms, medicines, and timing. The clinician… No single target; interpret A1c, fasting plasma glucose, fasting insulin, HOMA-IR,… →
At-home measure Continuous Glucose Monitor (CGM) A continuous glucose monitor is a small wearable sensor. It checks glucose in the fluid between your cells every few minutes. The report shows when… A CGM can show what the sensor read before, during, and after brain fog. You can then check whether the same timing happens again. One low or high reading… Not one universal range. For many adults with type 1 or type 2 diabetes, reports calculate… →
Lab Fasting Insulin Blood Test This blood test measures insulin after you have gone without calories for a set time. It is usually checked with fasting glucose so the two results can be… Read insulin with the glucose from the same blood draw, the hours you fasted, the lab method, your medicines, and the reason for the test. High insulin… Use the range on your lab report. Mayo lists 2.6 to 24.9 mcIU/mL for its current serum… →
Lab Fasting Plasma Glucose Blood Test This lab test measures blood sugar after at least 8 hours with no calories. It can help check for prediabetes, diabetes, medicine or illness effects, and… Fasting glucose gives one blood sugar result before eating. Poor sleep, illness, stress, medicines, a long fast, time of day, and slow handling of the… For adults who are not pregnant, ADA ranges are 99 mg/dL or less, 100 to 125 mg/dL, and… →
Lab HbA1c An HbA1c blood test estimates your average blood sugar over the past 2 to 3 months. It is used to screen for and diagnose prediabetes and diabetes, and to… HbA1c may help if you're very thirsty, urinate often, have blurred vision, lose weight without trying, or had a high glucose result before. It also helps… Use the standard ranges for screening and diagnosis. If you already have diabetes, use the… →
Lab HbA1c, Fasting Glucose, and Fasting Insulin Panel This blood draw checks HbA1c, fasting glucose, and fasting insulin together. HbA1c shows the average over recent months. Fasting glucose shows one morning… Glucose can fall in a prediabetes or diabetes range. Insulin can't diagnose either one. High insulin with glucose below those ranges may mean the body is… Read each result on its own. For people who are not pregnant, HbA1c is below 5.7%, 5.7% to… →
Lab HOMA-IR: Formula, Results, and Cutoff Limits HOMA-IR is a calculation from fasting glucose and insulin. It estimates how those two results balance while the body is at rest. It is used mostly in… An online calculator may label the number normal, early resistance, or severe resistance. Those labels can look more certain than the evidence. A useful… HOMA-IR uses fasting glucose and fasting insulin from the same blood draw. For HOMA1,… →
Lab Urine Organic Acids Analysis Clinical urine organic acids analysis looks for groups of metabolite changes that can support an investigation for inherited metabolic disorders. It… This test can matter after an abnormal newborn screen or when family history and symptoms point to an inherited metabolic disorder. Signs include acid… No universal score: the laboratory reports an age-aware profile of named metabolites,… →
Sleep
6 explainers
Test What it measures Why it comes up Type & access Range / context
At-home measure Actigraphy Sleep-Wake Tracking Actigraphy uses a small wrist-worn movement sensor, usually worn day and night, to estimate sleep timing, wake time, naps, regularity, and day-to-day… Poor sleep can make it hard to think. A wrist device can show when you sleep, how often you wake, and how your sleep changes across several days. It can't… Usually 7 to 14 days of usable sleep-wake data, interpreted with a sleep diary and the… →
Specialist Multiple Sleep Latency Test (MSLT) The Multiple Sleep Latency Test (MSLT) is a daytime lab test. It measures how quickly you fall asleep during several planned naps and whether REM sleep… The MSLT measures severe daytime sleepiness that affects work, school, conversation, cooking, or safe driving. It can support a check for narcolepsy or… There is no universal stand-alone normal range. Read the mean daytime nap latency, number… →
Specialist Overnight Sleep Study (PSG) An overnight sleep study, also called polysomnography or PSG, records sleep, breathing, oxygen, heart rhythm, movement, and video while a technologist… The thought of trying to sleep with sensors, wires, a camera, and someone watching the readings can feel worse than the appointment. You may worry that you… A usable study answers the question it was ordered for and records enough valid sleep and… →
Specialist Polysomnography (In-Lab Sleep Study) Polysomnography is an overnight sleep study watched by a technician. It records brain waves, eye movements, chin and leg movement, airflow, breathing… You can sleep for eight hours and wake feeling no more rested than when you went to bed. A report may say AHI 4.7 but also list the lowest oxygen level,… No single normal sleep score. In adults, an AHI below 5 events per hour is commonly… →
At-home measure Screen Time Audit A seven-day home record that adds context to phone or tablet logs. It can compare bedtime use, notifications, repeated checking, and specific screen tasks… A five-hour phone total may include work, school, directions, health care, video calls, games, reading, or passive scrolling. It misses laptop and TV time,… There is no universal adult daily screen-time cutoff. A useful seven-day audit keeps… →
Specialist UARS and RERA Scoring Review A respiratory effort-related arousal, or RERA, happens when harder or limited breathing ends in a brief brain-wave arousal. It does not meet the score for… A low AHI may look normal even when you wake with a dry mouth, headache, racing pulse, or unrefreshing sleep. Ask what the study measured and scored.… No single agreed UARS cutoff. Read the AHI, hypopnea rule, RDI definition, RERA index,… →
Medicines
3 explainers
Test What it measures Why it comes up Type & access Range / context
Screener Anticholinergic Burden Review This score adds up the effects of medicines that block acetylcholine. Acetylcholine helps with attention, memory, alertness, bowel movement, and urination. Review this score if brain fog, memory slips, dry mouth, constipation, trouble urinating, dizziness, falls, sleepiness, or confusion began after a new… The lowest safe score after reviewing every medicine, your age, symptoms, fall risk,… →
Lab Medication Depletion Panel A review that chooses blood tests based on the exact medicine and concern. A medicine may lower a nutrient, change a blood salt, affect an organ, or need… A premade vitamin bundle may miss the test a medicine actually needs. Long-term metformin can make B12 testing useful. Some people who use a proton pump… There is no standard medication depletion panel and no universal list of nutrients to… →
Specialist Medication Review A structured check of every prescription, store-bought medicine, supplement, inhaler, patch, cream, drop, injection, and as-needed drug. The review checks… A review can find a wrong list, repeated ingredients, a drug with no current job, a missed safety test, a side effect, or an interaction. It can also find… There is no normal score. The useful result is one reconciled medicine list, a reason and… →
Cognition & attention
10 explainers
Test What it measures Why it comes up Type & access Range / context
Specialist AASP Sensory Profile The Adolescent/Adult Sensory Profile is a set of questions for people age 11 and older. It asks how sound, light, touch, movement, taste, and smell affect… You may lose track of what you are doing in places that are bright, loud, crowded, or full of movement. AASP can show which sights, sounds, smells, or… A qualified clinician interprets quadrant classifications against daily function, age,… →
Self-check ACE Questionnaire The ACE Questionnaire is a short self-screen about adverse childhood experiences before age 18. The score counts types of exposure. It is not a diagnosis,… Hard events in childhood can still affect sleep, stress, mood, pain, relationships, and the way you use health care. These problems can make it harder to… 0 to 10 exposure count, interpreted with protective factors, current safety, symptoms, and… →
Self-check AQ-10 Autism Screening AQ-10 is a short autism screening form. It helps you and a clinician decide whether to discuss a full autism assessment. AQ-10 may help if brain fog gets worse after social time, noise, bright light, a sudden change, or switching between tasks. It may also help if you spend a… For adults, a score of 0 to 5 is below the NICE referral point. A strong lifelong history… →
Self-check ASRS ADHD Screener ASRS-v1.1 and ASRS-5 are adult ADHD screens with different questions and scoring rules. Check which one you have. Choose the version before you score the form. Use the ASRS-v1.1 guide for a v1.1 result. Use the instructions supplied with ASRS-5 for an ASRS-5 result. A score below the positive-screen cutoff for the ASRS version used. Read it with childhood… →
Self-check ASRS-v1.1 Adult ADHD Screener ASRS-v1.1 is a short adult ADHD screen. You answer six questions about your usual life during the past 6 months. The result can help you decide whether to… ADHD can feel like brain fog. You may know what to do but still leave a form unfinished, miss a bill or appointment, lose things, or wait for panic before… Usually fewer than 4 positive Part A answers on the 6-question adult screen. The score… →
Specialist Baseline Cognitive Assessment A baseline cognitive assessment records how you do on memory, focus, language, thinking speed, and planning tasks. It may be a short test such as MoCA,… Later scores are easier to compare when you use the same test in similar conditions. Bring examples from daily life too. A short clinic test may miss… Structured score plus real-life examples →
Screener BRIEF-A BRIEF-A is a set of questions for adults. It asks about planning, memory, self-control, and other thinking skills used in daily life. You can fill it out,… BRIEF-A can show where daily tasks break down. You may have trouble starting, changing tasks, remembering the next step, keeping things in order, catching… Use the scored report: T-scores, percentiles, validity scales, self-report versus… →
Specialist Neuropsychological Evaluation A specialist asks what has changed and reviews your records. You complete thinking tasks that fit the question. The specialist checks the scores and writes… A neuropsychological evaluation checks attention, memory, learning, language, thinking speed, planning, and problem-solving. You talk with the clinician,… There is no single score that means the whole evaluation is normal or abnormal. A… →
Specialist P300 ERP Test P300, also called P3, is a small electrical response from the brain. Scalp sensors record it while you notice a rare sound or image among many repeated… The test shows how the brain responded during one short attention task. It does not copy a long talk, a workday, standing, effort, poor sleep, pain,… There is no universal normal P300 latency or amplitude. Read the value only against the… →
Specialist QbTest for ADHD: Procedure and Results QbTest is an in-clinic computer task with motion tracking. The child version takes about 15 minutes and the adolescent and adult version about 20 minutes.… The report includes movement, missed targets, reaction times, wrong presses, percentiles, and Q-scores. It doesn't give a simple yes or no answer for ADHD.… There is no pass score or diagnostic QbTest cutoff. Q-scores compare performance with an… →
Stress & mood
4 explainers
Test What it measures Why it comes up Type & access Range / context
Self-check GAD-7 Anxiety Screener GAD-7 asks how often seven anxiety symptoms bothered you during the past two weeks. Each answer scores 0 to 3, for a total of 0 to 21. Keep the answers and… Worry can make it hard to focus, sleep, rest, or make decisions. GAD-7 gives the past two weeks a score. The answers can show whether anxiety changed… The total is 0 to 21. Scores are 0 to 4 minimal, 5 to 9 mild, 10 to 14 moderate, and 15 to… →
Self-check Mood Disorder Questionnaire (MDQ) A short adult questionnaire about past periods of unusually high or irritable mood, energy, activity, and risk-taking. It has 13 yes-or-no symptom… People often seek help while depressed, exhausted, or unable to focus. They may forget a past period of much less sleep, faster speech, risky choices,… The standard adult screen is positive only when all three parts are met: at least 7 of the… →
Screener PCL-5 PTSD Checklist The PCL-5 is a 20-item adult self-report checklist for PTSD symptoms linked to a stressful experience. It can screen for possible PTSD, organize intrusion,… Trauma-related sleep loss, intrusive memories, avoidance, feeling constantly on guard, low mood, detachment, and difficulty concentrating can all make… The 20 items each score 0 to 4 and the total runs from 0 to 80. A clinician may use 31 to… →
Screener PHQ-9 Depression Questionnaire PHQ-9 asks about nine depression symptoms during the past two weeks. Each answer scores 0 to 3, for a total from 0 to 27. Save every answer, the total,… Depression symptoms can make it hard to think, work, study, eat, sleep, or care for yourself. PHQ-9 shows how often each symptom happened. The same total… The nine items each score 0 to 3 and the total runs from 0 to 27. Published symptom bands… →
Immune & inflammation
20 explainers
Test What it measures Why it comes up Type & access Range / context
Lab ANA Blood Test An ANA blood test looks for antibodies that may appear in lupus and other diseases of the immune system. Healthy people can also have these antibodies. ANA may help when brain fog isn't the only symptom. Swollen joints, mouth sores, a rash after sun, or fingers that change color in the cold can support an… Negative, or a positive result read with the titer, pattern, symptoms, exam, age,… →
Lab Anti-dsDNA Blood Test This blood test looks for antibodies against double-stranded DNA. These antibodies are more closely linked to lupus than ANA, but the result must be read… Anti-dsDNA may help after a positive ANA if you also have signs of lupus. These include swollen joints, a rash after sun, mouth sores, fever, low blood… Negative, or read with the lab range, test method, ANA, symptoms, complement levels, urine… →
Lab C-Reactive Protein C-reactive protein (CRP) is made by the liver when there is inflammation in the body. The blood test can help check an infection, an inflammatory illness,… CRP may help when trouble thinking happens with fever, swollen joints, a gut flare, chest symptoms, or new pain. It can also monitor an inflammatory… Use the lab's unit and reference range. Standard CRP is usually interpreted as low, mildly… →
Lab C4a Complement C4a and Complement C4a are two names for the same plasma test. It measures a substance made when part of the immune system turns on. It isn't the same as a… The short and full names can make one test look like two. Check the test name, unit, and how the sample was handled. Save the result once. Use the range printed by the laboratory that ran the assay. Labcorp currently lists… →
Lab ESR Blood Test The erythrocyte sedimentation rate, also called ESR or sed rate, measures how far red blood cells fall in a tube in one hour. It can help check for… ESR can rise for many reasons, and a normal result does not rule out every kind of inflammation. Check the range on your report, your age and sex,… Use the performing laboratory's age-, sex-, and method-specific reference interval. ESR is… →
Lab Fecal Calprotectin Stool Test This stool test measures calprotectin, a protein that rises when certain white blood cells enter the gut lining. Doctors use it to look for gut… The same result can mean different things when checking new symptoms or following known IBD. Age, infection, medicines, and the lab method also matter. A… Use the range on your lab report and the reason for testing. Mayo calls under 50 mcg/g… →
Lab HLA-DR Genotype This one-time genetic test reports versions of HLA genes called alleles, such as DRB1, DQB1, and DQA1. These genes help immune cells recognize pieces of… A report may relabel unfamiliar gene codes as susceptible, multisusceptible, or dreaded. That can sound like a diagnosis. The genes cannot show an… There is no normal range, high result, or low result. HLA typing reports inherited… →
Lab hs-CRP An hs-CRP blood test measures very small amounts of C-reactive protein, a protein that rises with inflammation. It is most often used to add… hs-CRP may help when there is another reason to check inflammation. Those reasons include a recent infection, immune disease, bowel inflammation, smoke or… There is no one best number for every use. A result used for heart-risk review is read… →
Lab Interleukin-6 (IL-6) Blood Test This blood test measures interleukin-6 (IL-6), a protein that carries messages in the immune system. IL-6 can rise with infection, injury, inflammatory… A value of 3 pg/mL can be high on one report and normal on another. The methods, samples, and handling are different. Start with the reason for the test… Use the range printed by the laboratory that ran the test. Current US upper limits range… →
Lab LPS Antibody Blood Test (IgA, IgG, and IgM) This specialty blood panel measures three kinds of antibodies that bind to a bacterial material called lipopolysaccharide (LPS). The antibodies are IgA,… These antibody levels can change with exposure, the immune response, the test method, and time. The panel reports how antibodies bind to LPS, not whether… There is no standard target for LPS antibodies. Use the range printed for each test on… →
Lab MMP-9 (Matrix Metalloproteinase-9) A specialist blood test for matrix metalloproteinase-9 (MMP-9). This enzyme helps the body break down and rebuild tissue. White blood cells and other cells… A person can receive a result that looks high against an old 332 ng/mL target but sits inside the current laboratory interval. The number can also change… Use the interval on the report from the laboratory that performed the exact assay.… →
Lab Plasma Histamine Blood Test This test measures histamine in blood plasma at one moment. Histamine can rise during a sudden allergic or mast-cell event, but it leaves the blood… A normal sample taken too late can miss an earlier histamine release. A high result may come from collection or processing problems. Treating either result… Use the interval printed by the performing laboratory. One current Mayo-linked enzyme… →
Lab Prostaglandin D2 Urine Test: Collection and Results This specialty test may measure prostaglandin D2, or PGD2, directly in blood or urine. It may instead measure a more stable PGD2 breakdown product in… The label 'prostaglandin D2 test' can mean several different tests. Mayo measures urine 2,3-dinor-11beta-PGF2 alpha. Sheffield measures urine 11beta-PGF2… There is no universal prostaglandin D2 range. First match the result to the exact analyte,… →
Lab Rheumatoid Factor Blood Test A blood test for rheumatoid factor, a group of antibodies that most often includes IgM binding to IgG. RF can support an inflammatory-arthritis or… A positive RF can add evidence when someone has swollen joints, morning stiffness, pain after rest, or lower hand function. Dry eyes or mouth, rash, fever,… Use the upper limit printed by the performing laboratory. Current examples differ: Mayo… →
Lab Serum DAO (Diamine Oxidase) Activity Test This specialty blood test measures diamine oxidase activity in serum. DAO helps break down histamine outside cells and is produced mainly in the intestine,… A report may call low DAO proof of histamine intolerance, but the evidence does not support that shortcut. Many people without food reactions fall below a… Use the performing laboratory's assay, method, unit, and interval. Some reports label… →
Lab Serum Tryptase Blood Test A blood test that measures total tryptase released mainly by mast cells. A sample taken soon after a sudden systemic reaction can be compared with the… Serum tryptase can answer two different questions. During a sudden reaction, did the level rise enough above this person's usual baseline to support… Use the interval printed by the performing laboratory and keep acute and baseline results… →
Lab TGF-β1 A specialist blood test that measures transforming growth factor beta 1 in a defined plasma specimen. TGF-beta 1 helps regulate immune activity, cell… An older report may mark a result high above 2,382 pg/mL. The current version of the same referred test uses an upper limit of 22,062 pg/mL. Confirm the… Use the interval printed by the laboratory that performed the exact assay. Mayo's current… →
Lab tTG-IgA Celiac Blood Test A blood test for IgA antibodies against tissue transglutaminase (tTG), an enzyme in the body. It is the preferred first antibody test for most people being… Untreated celiac disease can affect digestion, iron, growth, bones, nerves, energy, and thinking. tTG-IgA can support the diagnosis. Read the value with… Use the performing laboratory's negative, weak-positive, and positive bands, expressed… →
Lab Urine N-Methylhistamine Test: Collection and Results A urine test for N-methylhistamine, a more stable breakdown product of histamine. It can use a full 24-hour collection or a timed spot sample and is… Histamine itself disappears from blood quickly, so a urine metabolite can preserve part of the signal long enough to measure. Interpretation depends on the… Use the performing laboratory's age-, specimen-, and method-specific interval. Current… →
Lab VEGF Blood Test A VEGF blood test measures vascular endothelial growth factor, a signal involved in angiogenesis, tissue response to low oxygen, wound repair,… VEGF is most useful when a clinician is checking for POEMS syndrome or another condition tied to blood-vessel growth. Use the specimen, assay, and laboratory interval printed on the report. Mayo's plasma VEGF… →
Infection & post-viral
13 explainers
Test What it measures Why it comes up Type & access Range / context
Lab Bartonella IgG/IgM Antibodies This blood test looks for IgG and IgM antibodies made in response to Bartonella. Most labs test for B. henselae and B. quintana. The result can support a… The result may help a clinician choose between watching symptoms, taking another blood sample, or testing tissue or Bartonella DNA. It helps only when a… Negative or below the lab cutoff. Read the result with the species, test method, titer,… →
Lab Bartonella PCR Bartonella PCR looks for Bartonella DNA in one sample. The sample may be blood, serum, plasma, spinal fluid (CSF), fluid from a lymph node, fresh tissue,… PCR may help a clinician choose care when a Bartonella illness is severe, rare, or hard to confirm. It is not a general test for brain fog. Not detected. Read it with the sample type, collection date, exposure, symptoms, immune… →
Lab Candida Antibody Panel (IgG, IgA, IgM) This blood test looks for three types of antibodies to Candida albicans: IgG, IgA, and IgM. Antibodies show that your immune system has met Candida. They… Candida lives on and inside many healthy people, so a positive antibody result doesn't always mean an active infection. Before treatment, match the result… Use the negative, equivocal, and positive cutoffs printed by the laboratory for each… →
Lab Co-infection Panel A co-infection panel looks for certain infections that may follow a tick or animal exposure. It often checks for Babesia, Anaplasma, Ehrlichia, Bartonella,… This panel may help when brain fog starts with signs of infection after a likely exposure. Examples include a tick bite, travel to an affected area, fever,… Negative, not detected, or below the reporting laboratory cutoff, interpreted with… →
Lab D-Arabinitol Urine Test Several types of Candida make D-arabinitol. Most blood and urine research studied very sick hospital patients, people with weak immune systems, and… This result often appears on an organic-acids or yeast panel. A high number is sometimes called proof of an intestinal infection, even though it cannot… Use the range from the lab that did the test. The sample, method, unit, creatinine… →
Lab EBNA IgG (Epstein-Barr Nuclear Antigen IgG) EBNA IgG is an antibody to part of the Epstein-Barr virus called EBNA-1. It usually appears after the first infection has passed and may stay for life.… A high EBNA IgG result often means an infection from months or years ago. It does not mean EBV is active again. The full antibody panel, illness dates,… There is no healthy target for EBNA IgG. Use the lab's negative, unclear, or positive… →
Lab EBV Antibody Panel (Reactivation Panel) An EBV antibody panel usually has VCA IgM, VCA IgG, and EBNA IgG. Some panels add EA-D IgG. Together, the results can show no past exposure, a recent first… VCA IgG and EBNA IgG can stay high for years after that infection. Treating those old antibodies as an activity score can waste money and delay checks for… There is no healthy target for EBV reactivation. Read VCA IgM, VCA IgG, EBNA IgG, and… →
Lab EBV Early Antigen D IgG (EA-D IgG) EA-D IgG is an antibody to an early part of Epstein-Barr virus. It can appear during a recent infection, but it may stay for years in healthy people. It… Read EA-D with the full antibody panel, illness dates, immune health, and any transplant plan. Together, these details show whether the result adds useful… There is no healthy target for EA-D IgG. Use the lab's not detected, unclear, or detected… →
Lab EBV VCA IgG (Viral Capsid Antigen IgG) VCA IgG is an antibody to the outer shell of Epstein-Barr virus. It appears during a first infection and usually stays for life. A positive result means… A report may mark VCA IgG high even when it means past infection. The flag only says the result crossed that test's positive cutoff. How big the number is… There is no healthy target for VCA IgG. Use the lab's negative, unclear, or positive call.… →
Lab EBV VCA IgM (Viral Capsid Antigen IgM) VCA IgM is an early antibody to the outer shell of Epstein-Barr virus. It often appears near the start of a first infection and usually goes away within 4… Positive IgM does not always mean a current EBV infection. A weak result may come from test interference or another infection. Some real first EBV… There is no healthy target for VCA IgM. Use the lab's negative, unclear, or positive call.… →
Lab IGeneX Lyme and Tick-Borne Panels IGeneX is a US specialty lab, not one test. An order may combine Lyme antibody screens, immunoblots, PCR, T-cell tests, culture-enhanced PCR, and tests for… One report may use several methods, test several germs, and show both company and standard rules. It is not one yes-or-no Lyme answer. One band, an old… There is no single normal IGeneX result. Read the panel code and each test on its own.… →
Lab Lyme Disease Immunoblot (Western Blot) A blood antibody test used after the first Lyme test is positive or unclear. It reports IgM and IgG antibodies to parts of Borrelia burgdorferi, the germ… The result is useful only with the first Lyme test, possible tick exposure, symptoms, and timing. There is no standalone healthy range or target band. In the US standard two-tier… →
Lab Lyme EIA/ELISA Two-Tier Antibody Test A Lyme EIA or ELISA is a blood test for antibodies to Borrelia, the bacteria that cause Lyme disease. It is the first part of a two-step check. Standard… The first result is easy to misread. Testing too early can give a negative result. A positive final result can come from an infection months or years ago… There is no universal ideal ELISA index or wellness target. Use the performing… →
Heart & circulation
7 explainers
Test What it measures Why it comes up Type & access Range / context
Lab D-Dimer Blood Test A D-dimer blood test measures pieces left when the body breaks down a blood clot. Clinicians use it with symptoms and a clot-risk check. In some people, a… A low D-dimer can be useful when symptoms and clot risk are low enough for a rule-out test. A high result is common after surgery, infection, pregnancy,… Use the cutoff printed by the lab for its test and FEU or DDU unit. A common cutoff is 500… →
At-home measure Heart Rate Monitoring: Pulse, Standing, Holter, and Wearables Heart monitoring may mean counting your pulse, using a watch, checking heart rate and blood pressure from lying to standing, or wearing an ECG monitor.… Brain fog may happen with faintness, a pounding heart, shortness of breath, trouble with exercise, illness, dehydration, anemia, thyroid changes, medicine… There is no single target for every kind of heart monitoring. Most resting adults are… →
At-home measure NASA Lean Test: Instructions and POTS Result Limits A supervised 10-minute standing check. After quiet rest lying flat, it records heart rate, blood pressure, and symptoms every minute while the person leans… Some people think clearly while lying down but feel lightheaded, weak, shaky, breathless, sick, or muddled after standing. A timed series shows whether the… There is no standalone normal NASA Lean Test score. Current POTS criteria use a sustained… →
At-home measure Orthostatic Blood Pressure Test A timed comparison of blood pressure and heart rate after resting flat and then standing. The standard bedside series can detect a sustained pressure fall… A report that says only 'orthostatics negative' can hide the part that matters. Was the baseline taken after 5 quiet minutes lying down? Were blood… For classic orthostatic hypotension in adults, the usual criterion is a sustained fall of… →
At-home measure Orthostatic Vital Signs and Active Stand Test A clinician-style active stand records blood pressure, heart rate, symptoms, and safety after a true lying baseline and across standing. A 3-minute series… The highest pulse or lowest pressure is only one part of the result. Record what changed, when it changed, when symptoms started, and whether standing… There is no single target called stable orthostatic vitals. Read the full timed series.… →
Specialist Tilt Table Test A tilt table test moves a strapped table from flat to nearly upright. Staff watch heart rhythm, heart rate, blood pressure, symptoms, and recovery. It can… The test may trigger dizziness, dim vision, nausea, weakness, a racing heart, muddled thinking, or fainting. Staff can then see what heart rate and blood… There is no single normal number. Read the continuous heart-rate and blood-pressure trace,… →
Specialist Transcranial Doppler Ultrasound Transcranial Doppler is a painless ultrasound. It sends sound waves through thin areas of the skull. The test measures the direction and speed of blood… TCD can follow blood-flow changes at the bedside and can repeat measurements without radiation. The result is disease and protocol specific. A velocity… There is no universal normal velocity for every person or purpose. Read each named artery,… →
Neurology & imaging
18 explainers
Test What it measures Why it comes up Type & access Range / context
Imaging ASL Brain Perfusion MRI Arterial spin labeling, or ASL, is part of an MRI scan. It measures blood flow in the brain by marking water in your own blood. It usually needs no… ASL can show where blood flow in the brain is high, low, or slow. The result may lead to more blood-vessel imaging, an EEG, or follow-up for a clear brain… A radiology report with no blood-flow change that matters for care. The radiologist also… →
Self-check Beighton Score The Beighton Score is a 9-point test for joints that bend farther than usual. It checks the little fingers, thumbs, elbows, knees, and a forward bend. The… This score may help if you have brain fog plus loose or painful joints, repeated injuries, fatigue, or poor body-position sense. The same goes for gut or… Age-aware 0 to 9 score: 6 or more before puberty, 5 or more from puberty through age 50,… →
Imaging Brain MRI A brain MRI makes detailed pictures of the brain. It can look for tumors, stroke damage, MS, fluid buildup, injury, infection, or a possible cause of… The scan works best when the order asks a clear question. Reasons include new brain or nerve signs, a seizure, a changed headache, head injury, cancer,… Radiology report interpreted with the exact reason for imaging, safety screening, contrast… →
Imaging Brain SPECT Scan Brain perfusion SPECT is a nuclear medicine scan. A small amount of radioactive tracer goes into a vein. A camera moves around the head, and a computer… A report may describe lower or higher tracer uptake in one brain area. Ask why you're having the scan and which steps it involved. Check what happened… No universal normal range. Read the tracer, protocol, injection state and timing, motion… →
Screener Central Sensitization Inventory The Central Sensitization Inventory, or CSI, has 25 questions. It asks about pain and other symptoms that often occur together. The score can guide a pain… CSI may help when thinking gets harder on the same days as pain, poor sleep, headaches, or dizziness. The same goes for gut or pelvic symptoms, bright… 0 to 100 score; 40 or higher is a common screening flag from research and clinic use, not… →
Imaging Cervical Flexion-Extension X-Ray This test takes separate side-view X-rays while you bend your neck forward and backward. It may help after neck surgery or when a clinician needs to check… The report may list movement in millimeters or degrees. First ask what the X-rays are for and whether you moved enough for a clear result. Then compare the… There is no universal normal cutoff. Read the named spinal level, movement achieved, image… →
Imaging Digital Motion X-Ray (Spinal Videofluoroscopy) Digital motion X-ray, also called spinal videofluoroscopy, records a series of spine X-rays while you move. It shows how the bones line up during movement.… Some people consider DMX after whiplash, long-term neck pain, dizziness, headache, or a normal MRI. Before paying for it, ask which movement or postsurgery… There is no single normal DMX range. Read the report with the scan method, spine levels,… →
Imaging DTI MRI (Diffusion Tensor Imaging) Diffusion tensor imaging, or DTI, is an MRI method that estimates how water moves through the brain's white matter. It can help map brain pathways before… Some clinics offer DTI after a concussion, crash, sports injury, normal CT, or normal MRI. In studies, some injured groups show average white-matter… There is no single healthy DTI number. FA, MD, tract maps, and z-scores change with the… →
Specialist Finger Tapping Test This test counts how many times you can repeat one finger movement in a set time. The classic version tests how fast each hand can press a tapping key. It… A slow result can show slower movement, a difference between hands, changing speed, or tiredness across trials. Pain, arthritis, injury, weakness, tremor,… There is no single normal tap count. Use scores for the same device and steps. Compare… →
Screener HIT-6 Headache Impact Test: Score and Meaning HIT-6 is a six-item patient questionnaire for adults with frequent headaches. It asks how often recent headaches affected pain, ordinary activity, the need… A pain rating cannot show whether headaches made you miss work, stop cooking, lie down, lose patience, or read the same sentence again. HIT-6 gives those… The total runs from 36 to 78. Common interpretation bands are 36 to 49 for little or no… →
Screener MIDAS Migraine Score: Disability Grades and Meaning MIDAS stands for Migraine Disability Assessment. It counts days when headaches stopped or greatly reduced work, school, home tasks, or social activities… A visit can miss the difference between having pain and losing parts of your life to it. MIDAS can show that you kept attending work but functioned at half… Add questions 1 to 5 only. Grade I is 0 to 5 days, Grade II is 6 to 10, Grade III is 11 to… →
Screener Pain Scales Pain scales are communication and tracking tools. A numeric rating scale or visual analog scale measures intensity. A faces scale offers another… Pain can pull attention away from conversation and reading, disturb sleep, limit activity, and interact with mood and medicine effects. A single intensity… A pain scale has no universal healthy target or diagnostic cutoff. On the common 0 to 10… →
Specialist Quantitative EEG (qEEG) Brain Mapping Quantitative EEG, or qEEG, uses software to measure a scalp EEG. It may report power, peak frequency, differences between sides, links between signals,… A qEEG report can look exact because it uses colors, percentiles, and z-scores. First check whether the recording was clean and whether the result changes… There is no universal normal qEEG brain map or diagnostic z-score cutoff. Read the raw… →
Specialist Rapid Alternating Movement Test In this short brain and nerve exam, you quickly turn one hand palm-up and palm-down. You may instead tap the palm and back of the hand on a surface or tap… The note “rapid alternating movements impaired” describes one part of the exam. Save which movement and side were tested. Also note problems with rhythm,… No universal tap count or time defines a normal bedside result. Clinicians compare rhythm,… →
Specialist Romberg Balance Test A supervised exam that compares standing with the eyes open and closed. It tests how vision, body-position sense, and the inner ear work together to… A chart may say “Romberg positive” but leave out the details. You need to know whether standing was steady with eyes open, what changed after closing them,… No universal normal time. In the classic bedside test, the clinician compares standing… →
Imaging Upright MRI MRI performed while sitting, standing, weight bearing, or in selected flexion and extension positions. It may show position-dependent changes in the spine… Symptoms that appear under load or in a particular position can make a positional question reasonable. The scan must answer a defined anatomical question.… There is no universal normal upright MRI measurement. Read the body region, field… →
Specialist Vestibular Assessment A specialist assessment of dizziness, vertigo, blurred vision with movement, unsteadiness, falls, or motion sensitivity. It may combine history, hearing,… The inner ears, eyes, brain, sensation, muscles, heart rhythm, blood pressure, medicines, and migraine can all affect balance. A planned set of tests can… There is no single pass or fail. Read the symptom history, bedside examination, hearing… →
Self-check Visual Contrast Sensitivity Test A visual contrast sensitivity test checks how faint a shape, stripe, or letter can become before it disappears into its background. It measures a different… Someone may read black letters on a white chart but still miss a curb in dim light or a face in shadow. An old glasses prescription, dry eye, cataract,… Use the named chart or digital method, its own scoring rules, and controlled viewing… →
Digestion & gut
8 explainers
Test What it measures Why it comes up Type & access Range / context
Lab GI-MAP Stool DNA Test GI-MAP is a branded stool test from Diagnostic Solutions Laboratory. It uses qPCR to look for DNA from selected microbes. Some orders also include tests… DNA from a disease-causing microbe may need a standard infection test. Calprotectin, pancreatic elastase, and hidden blood each need their own follow-up.… There is no single normal GI-MAP score or proven healthy-microbiome target. Each part of… →
Lab Hydrogen Breath Test This timed test measures hydrogen in breath after you drink a test sugar. Gut microbes make hydrogen when they break down the sugar. Glucose or lactulose… One red hydrogen number can hide the real result. A 20 ppm rise by 90 minutes after glucose or lactulose is not read the same way as a later rise after… There is no single healthy hydrogen range. After glucose or lactulose, a common North… →
Lab Hydrogen Sulfide Breath Test This test measures hydrogen sulfide (H2S), hydrogen, and methane in breath before and after a glucose or lactulose drink. It may add information when… A report may show one highest H2S number, but the science is still new. The commercial cutoff, a 2026 study rule, and a 2025 small-bowel research line… There is no single hydrogen sulfide cutoff. Save the lab, kit version, test drink, full… →
At-home measure Lactulose Hydrogen and Methane Breath Test A timed breath test after a lactulose drink, usually measuring hydrogen and methane. Lactulose is not absorbed, so it eventually reaches the colon and… A report may mark an early hydrogen rise as SIBO, but lactulose can reach the colon during the same time. Fast gut movement, dose, preparation, methane,… There is no single normal curve. A common North American rule uses a hydrogen rise of at… →
Specialist Methane Breath Test for Intestinal Methanogen Overgrowth A timed breath test that measures methane, usually with hydrogen, before and after a glucose or lactulose drink. Gut microbes called methanogens make… Methane is often buried in a report labeled SIBO. Methanogens are not bacteria and may live in the small or large intestine. Read the methane curve on its… No universal normal curve. North American consensus and the ACG guideline commonly use… →
Lab SIBO and IMO Breath Test A timed breath test taken before and after a glucose or lactulose drink. The lab measures hydrogen and methane made when gut microbes ferment the drink. It… You can follow every instruction and still test positive after lactulose but negative after glucose. The drinks move differently. Glucose is absorbed… Common North American rules use a hydrogen rise of 20 ppm or more above baseline by 90… →
At-home measure Trio-Smart Three-Gas Breath Test A branded mail-in breath test that measures hydrogen, methane, and hydrogen sulfide after glucose or lactulose. It can add a third gas to a selected… Gas curves can add context when bloating, abdominal pain, diarrhea, constipation, altered anatomy, or a motility problem makes breath testing reasonable.… Read the full hydrogen, methane, and hydrogen-sulfide curves with the substrate, timing,… →
Lab Zonulin Test A commercial blood or stool assay often sold as a test for leaky gut or intestinal permeability. Labs use different assays, samples, units, and cutoffs, so… It's easy to read too much into a high or low commercial zonulin result, because it's uncertain which protein the test picks up. Established symptom-led… There is no clinically validated universal serum or stool zonulin range. Record the… →
Kidney & organ function
7 explainers
Test What it measures Why it comes up Type & access Range / context
Lab CDT Blood Test CDT means carbohydrate-deficient transferrin. It is a blood test used to check for heavy alcohol use over the past few weeks. Read it with the lab method,… Alcohol can affect sleep, mood, the liver, nerves, nutrition, safety, and clear thinking. CDT may show heavy use over several weeks. One result cannot tell… Lab-specific percent CDT or disialotransferrin cutoff; older route data used <1.7%, while… →
Lab Cystatin C Cystatin C is a protein made by cells throughout the body. The kidneys remove it from the blood. A lab can use the blood level to estimate how well the… The same blood draw may give two eGFR results: one from creatinine and one from cystatin C. Different results do not mean the lab failed. One marker may… Use the reporting laboratory interval and calculated eGFR with paired creatinine, urine… →
Lab eGFR Estimated glomerular filtration rate, or eGFR, estimates how well your kidneys filter blood. Most adult reports use creatinine, age, and sex. Some use… eGFR can show that the kidneys may be filtering less blood. Kidney disease is more likely when low results last at least 3 months. Protein in urine,… Interpret the reported eGFR with the equation and marker used, age and body context,… →
Lab GGT (Gamma-Glutamyl Transferase) Blood Test This blood test measures gamma-glutamyl transferase, or GGT. The enzyme is found mainly in the liver and bile ducts. Read it with alkaline phosphatase, or… GGT is often checked when ALP is high or as part of a liver panel. Read high GGT with ALP, bilirubin, ALT, AST, symptoms, medicines, alcohol use,… Use the range for the person's age, sex, and lab method. Mayo lists below 178 U/L through… →
Lab Kidney Function Tests A kidney workup uses both blood and urine. Blood creatinine is used to estimate kidney filtering, called eGFR. Urine UACR checks whether a protein called… Kidney disease can cause no clear symptoms at first. A blood result may look fine while albumin or blood is appearing in urine. More advanced disease is… There is no single range for a kidney workup. Read creatinine and eGFR with urine UACR,… →
Lab Serum Creatinine A serum creatinine blood test measures a waste product made during normal muscle activity. Kidneys usually remove it from the blood. Clinicians put the… Creatinine can help when brain fog occurs with swelling, urine changes, nausea, trouble breathing, high blood pressure, diabetes, dehydration, severe… Use the reporting laboratory interval, eGFR, urine ACR, earlier results, muscle and diet… →
Lab UACR A urine albumin-to-creatinine ratio (UACR or ACR) measures albumin and creatinine in one urine sample. It can find early kidney-filter damage even when… Kidney filters can let albumin pass into urine while blood kidney results still look normal. UACR can find this early change. A repeat test, eGFR, other… Interpret the reported ratio and units with a clean first-morning repeat when needed,… →
Environment & exposure
9 explainers
Test What it measures Why it comes up Type & access Range / context
Lab Blood Mercury A blood mercury test measures mercury in your blood. It works best for recent methylmercury exposure from fish or seafood. For mercury vapor or other forms… High mercury exposure can harm the brain and nerves, kidneys, gut, and behavior. This test may help when brain fog or nerve symptoms began after eating… Lab-specific reference interval; interpret with seafood timing, exposure type, symptoms,… →
At-home measure Environmental Air Quality Review A room-by-room check of air, moisture, appliances, smoke, ventilation, and monitor readings at home, work, school, or during travel. It helps you find a… Smoke, cooking, fuel exhaust, damp materials, traffic, fragrance, heat, and poor ventilation need different fixes. Record the room, the exact finding or… There is no single normal indoor-air score. Review each question separately: carbon… →
At-home measure ERMI Mold Dust Test A lab uses quantitative PCR to measure DNA from 36 kinds of mold in settled dust. ERMI combines 26 molds linked with water-damaged homes and 10 molds often… One ERMI score cannot show where mold came from, whether it is alive, what you breathed in, or why you feel unwell. Keep the full species report and the… There is no EPA safe, unsafe, healthy, or medical cutoff. In the original 1,096-home US… →
Lab Heavy Metal Blood and Urine Testing Heavy metal testing measures named metals, often lead, mercury, arsenic, and cadmium, in blood or urine. It is most useful after a specific environmental,… A four-metal report is not one brain-fog score. Lead usually needs blood from a vein. Recent arsenic is best checked with urine that separates the forms of… There is no single healthy range for the whole panel. Read each metal with the right blood… →
At-home measure Indoor CO2 Monitor This monitor measures carbon dioxide (CO2) in room air, in parts per million (ppm). When people are the main source, the graph shows how the level changes… A rising graph can show that fresh air isn't keeping up with the people in the room. Test one safe ventilation change and see whether the level falls. A… No single CO2 number defines a healthy room. CDC uses below 800 ppm as one possible… →
At-home measure PM2.5 Monitor A home particle monitor that estimates fine particulate matter in micrograms per cubic meter. It can show when smoke, cooking, candles, traffic, dust, or… PM2.5 is the tiny particle pollution in smoke and fine soot. EPA says these particles can reach deep into the lungs, and some can enter the blood. A… There is no universal indoor medical cutoff for a consumer PM2.5 monitor. EPA's outdoor… →
Lab Provoked Urine Metal Test A provoked urine metal test gives DMSA or succimer, DMPS, EDTA, or another chelator before urine is collected. The drug binds and moves metals into urine,… The report can look alarming because it is often compared with people who did not receive a chelator. That is not a fair comparison. It may lead to repeat… There is no validated normal, borderline, toxic, or body-burden range for urine collected… →
Lab Urine Mercury Test A urine mercury test is mainly used when mercury vapor or another inorganic source is possible. Examples include a workplace, spill, contaminated cosmetic,… A urine number does not show the mercury form, exposure date, cause of symptoms, or amount in the brain. Urine is more useful for vapor and inorganic… Use the exact specimen and performing laboratory. A 24-hour result in µg/day, a… →
Lab Urine Mycotoxin Panel A urine mycotoxin panel looks for selected fungal toxins or their metabolites in urine. These measurements are used in exposure research and some specialty… People often reach this test after a water leak, musty building, online mold group, or long list of unexplained symptoms. The result can look decisive… No validated illness cutoff. A detected mycotoxin can show recent exposure or excretion,… →
General checks
13 explainers
Test What it measures Why it comes up Type & access Range / context
Lab CBC + CMP Blood Test Bundle CBC + CMP is a bundle of two blood panels. The CBC measures blood cells. The CMP measures 14 things linked to blood sugar, salts and fluid, the kidneys,… These panels can find anemia, other blood-cell changes, blood sugar or salt problems, and some kidney or liver problems. They don't include ferritin,… Use the reporting laboratory interval for every component, then read related changes… →
Lab Estradiol A blood test that measures estradiol, also called E2. Doctors may use it to check puberty, missing or irregular periods, ovarian or pituitary problems,… Estradiol changes during the menstrual cycle and may be hard to measure at low levels. The same result can mean different things based on cycle day,… There is no universal estradiol target. Use the reporting laboratory's method-specific… →
Lab FSH (Follicle-Stimulating Hormone) This blood test measures follicle-stimulating hormone, or FSH. The pituitary gland makes FSH. The test can help check puberty, periods, the ovaries,… The reason for testing changes what FSH means. Before age 40, four months of missing or irregular periods may raise concern about ovarian insufficiency.… There is no universal FSH target. Use the interval from the laboratory that performed the… →
Lab FSH and Estradiol Blood Test Panel This panel measures FSH and estradiol in one blood draw. The pituitary makes FSH. Before menopause, the ovaries make most estradiol. The pair can help… Estradiol can lower FSH. Early in a cycle, high estradiol can make FSH look normal when it is not. Low estradiol with high FSH points more toward the… There is no universal target for the pair. Use both laboratory intervals, the assay… →
At-home measure Heart Rate Variability (HRV) Heart rate variability (HRV) measures small changes in the time between heartbeats. A report may show RMSSD, SDNN, frequency measures, or a brand's… HRV changes with the device, measure, recording time, body position, breathing, and reading quality. A normal swing can look scary when you compare… There is no single healthy HRV number. Save the exact measure, units, device, recording… →
Lab Luteinizing Hormone (LH) Blood Test A blood test for luteinizing hormone, or LH, which is made by the pituitary gland. LH helps check ovulation, missing periods, fertility, ovarian or… The same LH number can mean different things. LH rises for a short time around ovulation and is often higher after menopause. It may rise when the ovaries… There is no universal LH target. Use the interval printed by the laboratory that performed… →
Lab Progesterone This blood test measures progesterone in serum. Doctors use it to check ovulation timing, the luteal phase, early pregnancy support, abnormal bleeding, or… Progesterone changes sharply across the menstrual cycle and rises during pregnancy. That makes timing the test as important as the number. For brain fog,… There is no single progesterone target. Interpretation depends on sex, pregnancy status,… →
Lab Prolactin This blood test measures prolactin, a hormone made by the pituitary gland. Prolactin helps control milk production and reproductive hormones. Doctors may… When prolactin stays high, it can lower LH and FSH. This may lower estrogen or testosterone and affect periods, fertility, sex drive, erections, bones,… Use the lab's sex, pregnancy, breastfeeding, medication, and assay-specific interval.… →
Lab Secretory IgA (sIgA) Stool or Saliva Test Secretory immunoglobulin A is an antibody found at body surfaces such as the mouth and intestine. Commercial tests may measure it in stool or saliva, but… A stool or saliva sIgA result shows one value from one test method. It is different from the blood test used to check for immune deficiency or celiac… There is no universal sIgA range. Use the exact specimen, assay, unit, age context,… →
Lab Serum Osmolality A serum osmolality test describes the concentration of dissolved particles in the water part of blood. A laboratory can measure it directly, usually by… Serum osmolality helps check water balance, sodium problems, marked thirst or urination, very high blood sugar, and some suspected poisonings. Large or… Use the reporting laboratory interval, measured or calculated method, sodium, glucose,… →
Lab Serum Potassium A potassium blood test measures the small amount of potassium outside your cells. Almost all of your potassium is inside cells. The body keeps the amount… Potassium helps nerves, muscles, and the heart's electrical system work. A result that is truly low or high can cause fatigue, weakness, cramps, tingling,… Use the reporting laboratory interval, symptoms, ECG context, kidney function, medicines,… →
Lab Serum Sodium A sodium blood test measures the concentration of sodium in the liquid part of blood. It is mainly a clue about the balance between sodium and water, not a… A sodium result can matter when brain fog starts with other symptoms. These may include marked fatigue, headache, nausea, unusual thirst, urine changes,… Use the reporting laboratory interval, symptoms, speed of change, glucose, fluid balance,… →
Lab TNF-alpha Blood Test A specialist blood test that measures tumor necrosis factor alpha, usually in serum or plasma. TNF-alpha is an immune signaling protein. One blood result… TNF-alpha is biologically important, but the blood test has a narrower clinical role than the name suggests. ARUP describes its current serum test as… Use the performing laboratory's specimen, assay, unit, and reference interval. Current… →
No matching test explainer.
Try a test name, a biomarker such as ferritin or TSH, a type such as sleep study, or a broader term.
How tests fit in
What makes a brain fog test useful?
Read each result together with your symptoms, the timing, your health history and your other findings. Before you decide whether to ask a clinician about a test, read its page to see what the test can tell you.
Save useful checks, notes and results in My Fog →