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Doctor appointment handout

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Questions to ask about cortisol tests and brain fog

Cortisol helps control blood pressure, blood sugar, inflammation, energy, and how your body responds to stress and illness. Stress can raise cortisol briefly, but feeling stressed or struggling to think doesn't by itself mean you have a cortisol disorder. Testing may help when brain fog appears with specific body changes or steroid medicine use.

Start here The brain fog, any body symptoms, when they began, and any steroid you take or recently stopped. Bring Bring a list of every medicine and supplement you use. Include any steroid tablets, creams, inhalers, sprays, eye drops, or injections and when you last used them. Ask I would like to discuss whether too little or too much cortisol, a steroid medicine, or another health problem could be contributing to my symptoms. Would cortisol testing be useful? Know Cortisol changes during the day. One random result can be hard to understand because timing, illness, pregnancy, estrogen, and medicines can change the cortisol result.

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Cortisol and Brain Fog: Doctor Visit Checklist, a doctor appointment handout from What Is Brain Fog.
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What to explain

Explain what has changed and why you want to discuss cortisol.

I'd like to talk about my brain fog and other symptoms. Could too little or too much cortisol, a steroid medicine, or another health problem be adding to them? Can we go over what's changed and decide if cortisol testing would help?

Questions to take in

Ask which cortisol problem your doctor is checking for and why that test was chosen.

  1. Which problem are you checking for: adrenal insufficiency, Cushing syndrome, steroid suppression, pituitary disease, or a medicine effect?
  2. Which sample method and collection time can answer that concern, and what medicines or activities should I change before collection?
  3. Could any tablet, injection, inhaler, spray, eye drop, cream, supplement, opioid, estrogen product, or anti-seizure medicine change my cortisol or the test result?
  4. Should we check ACTH, sodium, potassium, glucose, renin, aldosterone, thyroid tests, CBC, ferritin, B12, or orthostatic blood pressure at the same visit?
  5. If the first result is low, high, or between clear cutoffs, what repeat test, stimulation test, suppression test, or specialist review would follow?
  6. Do my pregnancy, oral estrogen, shift work, recent illness, kidney disease, alcohol use, or sleep schedule change the test you would choose?
  7. What symptoms mean I should use urgent care, and do I need written steroid-withdrawal or adrenal-crisis instructions?
  8. If adrenal disease is unlikely, which specific cause should we check next? And what can I safely do now about sleep, meals, fluids, activity, caffeine, or alcohol?

Cortisol tests and medicine review

What each cortisol test checks and why the timing matters.

There is no single cortisol test for every concern. Morning blood can help check possible low cortisol. Late-night saliva, 24-hour urine, or a dexamethasone test may help check possible high cortisol.

8 AM Cortisol Blood Test

An 8 AM cortisol can help assess possible adrenal insufficiency. It is often paired with ACTH, and a middle result may need repeat timing, stimulation testing, or endocrinology review.

Read the test guide

ACTH Stimulation Test

An ACTH stimulation test measures cortisol before and after a synthetic ACTH injection. It checks whether the adrenal glands can respond, but recent pituitary disease can complicate interpretation.

Ask your doctor

Cortisol Testing Overview

The cortisol overview explains why morning blood, late-night saliva, 24-hour urine, dexamethasone suppression, and research-style daily curves cannot be used as substitutes for one another.

Read the test guide

Late-night salivary cortisol

Late-night salivary cortisol checks whether cortisol stays too high when it normally falls. It's a Cushing screen, not a general test for stress, fatigue, or adrenal fatigue.

Read the test guide

24-Hour Urinary Free Cortisol

A 24-hour urine collection measures free cortisol released across a full day. Missing urine, kidney problems, excess fluid intake, and incorrect timing can make the result unreliable.

Read the test guide

Overnight Dexamethasone Suppression Test

An overnight dexamethasone suppression test checks whether a prescribed dose of this steroid lowers morning cortisol. Medicines, estrogen, pregnancy, and some conditions can change the result.

Ask your doctor

Medication Review

A medication review finds steroid exposure and medicines that alter cortisol tests. Steroids include tablets, injections, inhalers, nasal sprays, eye drops, creams, and some unlabelled supplements.

Read the test guide

Orthostatic Blood Pressure Test

Orthostatic blood pressure measures lying and standing blood pressure and pulse. A fall can support assessment of dehydration or adrenal insufficiency, but it does not identify the cause.

Read the test guide

Serum Sodium

Sodium, potassium, and glucose can show effects that sometimes occur with adrenal disease. Normal results do not rule out every form of adrenal insufficiency.

Read the test guide

Before the appointment

Bring symptom dates, every medicine, earlier results, and examples of what the brain fog stops you doing.

The date your brain fog and body symptoms began, what changed first, whether they're constant or come and go, and whether illness, surgery, injury, pregnancy or steroid use came beforehand.

Every prescription, over-the-counter product, supplement, and unlabelled powder. Photograph both sides of each package and record the dose and last-use time.

Every steroid used during the past year, including tablets, injections, inhalers, nasal sprays, eye drops, skin creams, scalp products, and medicines received outside regular care.

Earlier cortisol results with the sample method, value, unit, laboratory interval, collection date and time, wake time, medicines, illness, pregnancy, estrogen use, and clinician interpretation.

Blood pressure, weight, glucose, sodium, potassium, ACTH, thyroid, CBC, ferritin, B12, sleep-study, pituitary, and adrenal results when available.

A seven-day note of sleep times, shift work, meals, caffeine, alcohol, steroid timing, dizziness, vomiting, bruising, weakness, blood pressure, brain fog, and one difficult daily task.

Two examples of reading, driving, work, school, cooking, medicine use, or conversation becoming slower, less accurate, or unsafe.

Steroid medicines can change how much cortisol your body makes.

For example: I used prednisone tablets for six weeks, reduced the dose two weeks ago, and then developed vomiting, dizziness, weakness, and trouble thinking.

How the doctor assesses this

Body changes and medicine history that may make cortisol testing useful

  • Possible low cortisol: dizziness when standing, weight loss, nausea, vomiting, stomach pain, salt craving, darker skin, low blood pressure, low sodium, or low blood sugar.
  • Possible high cortisol over time: easy bruising, wide purple stretch marks, weak arms or legs, body or face weight gain, high blood pressure, high blood sugar, fractures, or slow growth.
  • Steroid medicine timing: symptoms began while taking, reducing, or stopping a steroid tablet, injection, inhaler, nasal spray, eye drop, or skin cream.

When sleep, thyroid, anemia, blood sugar, infection, medicines, alcohol, anxiety, or depression may explain the symptoms

  • Adrenal insufficiency becomes more likely with weight loss, low blood pressure, dizziness, nausea, vomiting, abdominal pain, salt craving, darker skin, low sodium, low glucose, or recent steroid withdrawal.
  • Cushing syndrome becomes more likely when several changes get worse together. These can include easy bruising, wide purple stretch marks, muscle weakness, facial or trunk weight gain, high blood pressure, or high glucose.
  • A medicine effect becomes more likely when symptoms follow starting, reducing, or stopping a steroid tablet, injection, inhaler, nasal spray, eye drop, cream, or supplement.
  • Poor sleep, sleep apnea, thyroid disease, anemia, diabetes, infection, depression, anxiety, alcohol, menopause, and several medicines can cause similar fatigue and thinking problems without an adrenal disorder.
  • Stress can worsen sleep, concentration, appetite, and energy. A private saliva curve can't by itself show that the adrenal glands are failing or diagnose Cushing syndrome.

What to understand before choosing care

What your doctor needs to decide before ordering a cortisol test.

  • Do not stop, reduce, or skip a prescribed steroid to change a cortisol result. Sudden withdrawal after longer use can cause adrenal insufficiency and may become dangerous.
  • Ask which condition the clinician is checking before collecting a sample. Morning blood, late-night saliva, 24-hour urine, ACTH stimulation, and dexamethasone suppression serve different purposes.
  • List every possible steroid exposure. Include pills, injections, inhalers, nasal sprays, eye drops, skin creams, joint injections, bodybuilding products, and supplements.
  • Do not use adrenal extracts, hydrocortisone, cortisol blockers, or hormone supplements to treat an unconfirmed result. They can change testing, interact with medicines, or cause harm.
  • When adrenal tests are reassuring, ask for help with sleep, regular meals, hydration, suitable activity, caffeine, alcohol, and stress. These steps may help symptoms while the cause is investigated.

What the research found

What 2024 to 2026 research found about cortisol problems and thinking.

A 2024 guideline states that at least 1% of the population uses long-term glucocorticoids and may face adrenal suppression. Risk varies by dose, duration, strength, route, and how each person responds.

A 2025 systematic review included 40 studies and 2,603 people with Cushing syndrome. It linked higher cortisol before treatment and longer uncontrolled disease to worse or lasting thinking problems.

A 2025 single-center study included 107 people with Cushing disease. Fifty-eight had cognitive impairment and 49 did not, so the results cannot predict one person's outcome.

A 2026 review found adults with adrenal cortisol insufficiency often report problems with memory, planning, and organizing.

A 2026 review of 74 published Cushing cases reported cognitive complaints in 32%. Case reports select unusual patients, so 32% is not a population rate.

A 2025 endocrine review states that adrenal fatigue is not a proven diagnosis. Commercial questionnaires and saliva profiles do not establish adrenal failure.

Stress can affect sleep, mood, attention, blood pressure, glucose, and daily cortisol release. Those effects do not mean that ordinary stress has damaged the adrenal glands.

How age, sex, pregnancy, estrogen, and night work can change cortisol testing.

Children with Cushing syndrome may gain weight while growing more slowly. Low glucose can be more noticeable in children with adrenal insufficiency, so pediatric endocrinology assessment is important.

NIDDK reports that Cushing syndrome affects about three times as many women as men. Addison disease is also more common in women, but either condition can affect any sex.

Cushing syndrome and Addison disease most often appear between ages 30 and 50, but both can occur in children, younger adults, and older adults.

Pregnancy and oral estrogen can raise total blood cortisol. Cushing testing during pregnancy differs, and known adrenal insufficiency needs specialist review during each trimester.

Older adults may have several steroid exposures, medicines, diabetes, osteoporosis, infection, cancer treatment, or pituitary disease. These details can matter more than a single cortisol result.

Night work, rotating shifts, jet lag, and irregular sleep can change cortisol timing. Collection time should be compared with the person's actual sleep and wake schedule.

If the answer is no

If your doctor will not order a random cortisol test

A random cortisol value isn't a reliable general test for feeling stressed, tired or muddled. The Endocrine Society recommends against widespread Cushing syndrome testing and against random serum cortisol or ACTH for that diagnosis. Testing should start only when the history and physical features make a defined cortisol disorder plausible, using a method suited to that question.

What changes the answer

  • Name the disorder you are worried about. Cushing syndrome, adrenal insufficiency and ordinary stress are different questions. Ask which one your symptoms could reasonably support.
  • Bring the full steroid history. Tablets, inhalers, creams, injections and supplements can change the assessment. Include the product, dose, schedule and last use.
  • Ask which proven test fits. The timing and method depend on whether the concern is too much cortisol, too little cortisol, or a pituitary problem. A random result may be hard to interpret.
  • Ask when to review cortisol testing again. Ask which worsening physical signs, medicine changes or abnormal results would need an endocrinologist or a different first test.
Endocrine Society: diagnosis of Cushing syndrome

United States, United Kingdom, and Australia

Who to contact about Cortisol and Brain Fog.

US United States

Book primary care or endocrinology. Bring symptom dates, every steroid exposure, earlier results, pregnancy or estrogen details, sleep timing, and daily examples. Ask which named condition and test are being considered.

  • Start with a primary care clinician when symptoms are stable. Bring the steroid list and ask whether you need an endocrinology referral before specialized cortisol testing.
  • Endocrine Society guidance uses different tests for possible adrenal insufficiency and Cushing syndrome. It advises Cushing screening only for people with worsening or unusual signs.
  • NIDDK says doctors commonly confirm Cushing syndrome with more than one test. To diagnose adrenal insufficiency, they most often use ACTH stimulation.
Read Endocrine Society and NIDDK adrenal guidance
UK United Kingdom

See a GP. Bring symptoms, steroid details, earlier cortisol results, sleep timing, pregnancy or estrogen details, and daily examples. Ask whether NICE referral or urgent steroid-safety advice applies.

  • Start with a DR for stable symptoms, medicine review, and an 8 to 9 AM cortisol when the DR suspects adrenal insufficiency.
  • NICE 2024 provides morning cortisol thresholds for referral and explains when oral glucocorticoid withdrawal needs specialist advice.
  • An endocrinology service assesses suspected Cushing syndrome, confirmed or uncertain adrenal insufficiency, pituitary disease, pregnancy, and difficult steroid withdrawal.
Read NICE NG243 adrenal insufficiency guidance
AU Australia

See a GP. Bring symptoms, every steroid exposure, earlier results, sleep timing, pregnancy or estrogen details, and examples. Ask whether you need endocrinology or urgent steroid-safety advice.

  • Start with a GP for stable symptoms, steroid review, blood pressure, and tests chosen for suspected low or high cortisol.
  • Healthdirect explains that cortisol changes through the day and that blood, saliva, and urine testing may be used for Cushing syndrome or Addison disease.
  • An endocrinologist assesses abnormal or uncertain results, pituitary or adrenal disease, pregnancy, children, and difficult steroid withdrawal.
Read Healthdirect and Hormones Australia adrenal guidance

Safety

Show how it affects daily life

  • For seven days, note wake time, hours slept, shift work, meals, caffeine, alcohol, steroid use, dizziness, nausea, bruising, weakness, brain fog, and one daily task that got harder.
  • If you already own a validated monitor, record seated and standing blood pressure only as instructed. Stop if you may fall, and seek advice for fainting or very low readings.
  • Eat and drink regularly until your appointment, unless a clinician told you otherwise. Note whether skipped meals, dehydration, alcohol, or heavy exercise clearly makes symptoms worse.
  • Use a consistent sleep and wake time when possible. Record snoring, gasping, morning headache, dry mouth, and daytime sleepiness because sleep disorders can resemble cortisol problems.
  • It's unsafe to test yourself by skipping steroid medicine, taking a supplement, fasting, overexercising, staying awake, or creating stress.
  • Save each cortisol result with the sample method, collection time, wake time, value, unit, laboratory interval, medicines, pregnancy or estrogen status, illness, and clinician explanation.

Source checked

Sources behind this handout.

  1. Nieman LK et al. The diagnosis of Cushing's syndrome: an Endocrine Society clinical practice guideline. Journal of Clinical Endocrinology and Metabolism. 2008. PMID: 18334580.

    Source

  2. Beuschlein F et al. Diagnosis and therapy of glucocorticoid-induced adrenal insufficiency: joint European Society of Endocrinology and Endocrine Society guideline. Journal of Clinical Endocrinology and Metabolism. 2024. PMID: 38724043.

    Source

  3. Katragadda A et al. Cognitive decline in Cushing's syndrome: a systematic review. Journal of Neuroendocrinology. 2025. Forty studies and 2,603 participants. PMID: 39506264.

    Source

  4. Sun Y et al. Prolonged high-concentration cortisol exposure and cognitive function in Cushing's disease. Journal of Alzheimer's Disease Reports. 2025. PMID: 40297056.

    Source

  5. Ben-Shlomo A et al. Cognitive assessment in adults with adrenal cortisol insufficiency. Endocrine Reviews. 2026. PMID: 40899005.

    Source

  6. Lhul RVDS et al. Cushing's syndrome: a systematic review of psychiatric and cognitive symptoms in case studies. Archives of Endocrinology and Metabolism. 2026. PMID: 41945628.

    Source

  7. McDermott MT. Pseudo-endocrine disorders: recognition, management, and action. Journal of the Endocrine Society. 2025. PMID: 39749108.

    Source

  8. National Institute for Health and Care Excellence. Adrenal insufficiency: identification and management. NG243. Published August 28, 2024.

    Source

  9. National Institute of Diabetes and Digestive and Kidney Diseases. Cushing's syndrome: symptoms, who is affected, and diagnostic tests.

    Source

  10. Healthdirect Australia. The role of cortisol in the body. Reviewed September 2024.

    Source