What to explain
Explain the pituitary risk before asking for a growth hormone test.
I would like to discuss whether my pituitary history and current changes justify checking for growth hormone deficiency. I brought the date of my pituitary condition, brain injury, surgery, radiation, or childhood diagnosis, plus earlier hormone results. Could we review growth hormone and the other pituitary hormones together before deciding which tests I need?
Questions to take in
Ask how the medical history changes the test plan.
- Does my pituitary, brain-injury, radiation, surgery, or childhood history make growth hormone deficiency likely enough to test?
- Could nutrition, liver disease, kidney disease, thyroid disease, diabetes, severe illness, or a medicine explain my IGF-1 result?
- If I need a stimulation test, which is safest for me and how do I prepare? How will my body size and the lab's method change the cutoff?
- Which other pituitary hormones need checking now, especially cortisol and free T4?
- Do my headaches, vision symptoms, hormone results, or earlier pituitary condition mean I need a pituitary MRI?
- If deficiency is confirmed, which symptoms, test results, side effects, and daily abilities will we use to judge whether treatment helps?
- If growth hormone deficiency is not found, which cause of my brain fog or low energy should we assess next?
Tests an endocrinologist may consider
Which tests may confirm deficiency and check the rest of the pituitary.
IGF-1 is an initial blood test. Adults may need a supervised stimulation test because one IGF-1 or random growth hormone result can't confirm adult deficiency. Cortisol and thyroid safety, other pituitary hormones, imaging, and bone health are checked only when the history makes them useful.
IGF-1 Blood Test
This test measures a steadier sign of growth hormone activity. Your doctor reads the result alongside your age, sex, nutrition, liver, kidney and thyroid health, diabetes, illness, pregnancy and hormone medicines.
Ask your doctorGrowth Hormone Stimulation Test
Measures growth hormone several times after a medicine should make the pituitary release it. The test, preparation, safety rules, and cutoff depend on the person and clinic.
Ask your doctor8 AM Cortisol Blood Test
Checks whether morning cortisol may be too low. Untreated low cortisol can be dangerous, and it must be dealt with before growth hormone treatment.
Read the test guideThyroid Function Tests
Checks TSH with free thyroid hormone levels. Pituitary thyroid disease may show low free T4 without the high TSH expected in ordinary primary hypothyroidism.
Read the test guideProlactin Blood Test
Checks a pituitary hormone that can affect periods, fertility, libido, and sex hormones. A high result has several possible causes and does not prove a tumor.
Read the test guideBrain MRI
Shows the pituitary area and nearby brain structures. Imaging is useful for selected symptoms, hormone results, or known pituitary disease, not as an automatic brain-fog test.
Read the test guideDEXA Bone Density Scan
Measures bone density. It may be useful after confirmed long-term deficiency, a fracture, or another bone-risk factor, but is not required for every person.
Ask your doctorBefore the appointment
Bring the records that show what happened to the pituitary.
Bring records for any tumor or surgery involving the pituitary gland or brain. Include radiation to the head, severe brain injury, bleeding around the brain, childhood hormone treatment, or an inherited pituitary condition.
Bring every earlier IGF-1 and growth hormone stimulation report. Add cortisol, thyroid, prolactin, LH, FSH, estradiol, testosterone, sodium, glucose, brain scan, and bone-density results.
List every hormone, steroid, birth-control, thyroid, diabetes, pain, and opioid medicine you use. Add supplements, growth hormone products, and peptides.
Write when thinking, energy, strength, body fat, or ability to exercise changed. Add headaches, vision changes, thirst, urination, periods, sex drive, or sexual function.
For a child, bring the complete growth chart, birth history, parent heights, puberty history, nutrition history, and any height measurements from school or earlier clinics.
For an adult treated for growth hormone deficiency as a child, bring the childhood diagnosis, stimulation-test result, MRI or genetic result, treatment dates, and reason treatment stopped.
The endocrinologist needs the reason for testing. A symptom list alone isn't enough.
How the doctor assesses this
Medical history that can make testing reasonable
- A pituitary or nearby brain tumor, surgery, radiation, inflammation, or known structural condition.
- A significant brain injury, childhood growth hormone deficiency, or several other pituitary hormone deficiencies.
- Slowed height growth in a child or new strength, body, bone, or exercise changes in an adult with pituitary risk.
Reasons to check more common causes of brain fog first
- There is no childhood growth problem or disease in the brain areas that control hormones. There is also no major brain injury, radiation to the head, surgery, or shortage of another pituitary hormone.
- A correctly performed growth hormone stimulation test is normal using the cutoff for that test, laboratory method, age, and body size.
- IGF-1 returns to the usual range after poor nutrition, liver disease, thyroid disease, poorly controlled diabetes, or severe illness is treated.
- A child's height continues along the expected growth curve and the pediatric assessment identifies another reason for short stature.
- Sleep loss, anemia, thyroid disease, depression, medicine effects, or another condition explains the symptoms better and improves with treatment.
What to understand before choosing care
What the clinician needs to decide before ordering growth hormone tests.
- Growth hormone deficiency is rare. In adults, tiredness, trouble thinking, weight change, or low mood cannot diagnose it because many more common conditions cause the same symptoms.
- Adult testing is most useful after disease, surgery, or radiation involving the brain areas that control hormones. Major brain injury, childhood growth hormone deficiency, or shortages of several other pituitary hormones also raise concern.
- A random growth hormone blood result is not useful because growth hormone rises and falls in bursts. IGF-1 is steadier, but one IGF-1 result cannot confirm or exclude adult deficiency.
- Adult diagnosis usually needs a growth hormone stimulation test. The test and cutoff depend on age, body size, medical history, medicines, and the laboratory method.
- Growth hormone treatment is for confirmed deficiency under specialist care. It is not an anti-aging, bodybuilding, weight-loss, or general brain-fog treatment.
What the research found
What current guidance says about IGF-1, stimulation testing, and adult symptoms.
Adult symptoms often have many possible causes. Age, sex, and body size affect stimulation-test results. A 2024 review found both. It did not identify one symptom that diagnoses deficiency.
A 2025 international expert panel agreed that testing belongs in an appropriate medical setting. Adult result cutoffs should be specific to the stimulation test used.
A 2006 meta-analysis found group differences in attention and memory, but it combined 13 small studies. It cannot show that growth hormone deficiency caused one person's brain fog.
The strongest treatment evidence concerns body composition, exercise ability, bone health, and quality of life in confirmed severe deficiency. It does not promise that brain fog will improve.
No food, supplement, sleep schedule, exercise plan, peptide, or home test can confirm or treat pituitary growth hormone deficiency.
How growth hormone assessment changes in children, adults, and older adults.
In children, slowed height growth is the main concern. The Endocrine Society notes that many affected children grow less than 2 inches, or 5 centimeters, in a year.
Children who drop across height percentiles need a pediatric growth assessment. Short height alone does not prove growth hormone deficiency.
Many people treated for isolated growth hormone deficiency in childhood need retesting after growth ends. A permanent genetic or structural pituitary condition may change that decision.
Older adults should not be diagnosed from an age-adjusted low IGF-1 alone. Normal aging lowers growth hormone activity, and testing still needs a pituitary or hypothalamic reason.
IGF-1 ranges change with age and sex. Pregnancy and estrogen pills can affect the result. The hormone specialist needs the pregnancy and medicine history.
If the answer is no
If your doctor will not diagnose growth hormone deficiency from one blood test
Growth hormone rises and falls, so one random blood level cannot diagnose a shortage. The Endocrine Society usually recommends a stimulation test when adult growth hormone deficiency is strongly suspected. Some people with known pituitary disease and several other low pituitary hormones may not need that test.
What changes the answer
- Bring your pituitary history. Include pituitary tumors, surgery, radiation, head injury, childhood growth hormone deficiency, and results for other pituitary hormones.
- Bring signs beyond fatigue or brain fog. These symptoms have many causes. Ask which part of your history or exam makes growth hormone deficiency likely.
- Ask whether a stimulation test fits. This test checks whether your body can release growth hormone when prompted. A random growth hormone result cannot do that.
- Ask for an endocrine review when several hormones are affected. Bring hormone results and pituitary scans. These findings can change whether you need more testing.
United States, United Kingdom, and Australia
Where to seek pituitary assessment.
US United States
Ask whether endocrinology testing is justified. Primary care or the pituitary clinician can review risk factors, order initial hormone tests, and refer for specialist stimulation testing when needed.
- Start with primary care or the clinician who manages the pituitary condition. Ask for endocrinology when the history gives a medical reason to test.
- Confirmation usually needs a specialist stimulation test. That test may be unnecessary when a permanent inherited or structural cause from childhood is already established.
- Insurance often asks for the pituitary history and stimulation-test evidence before it covers adult growth hormone treatment.
UK United Kingdom
Request endocrine review when the history supports it. A GP or pituitary team can review initial hormone results and refer to endocrinology for supervised stimulation testing when needed.
- A GP can review symptoms and known pituitary history. A hormone service usually arranges and reads the growth hormone stimulation test.
- Newcastle's 2026 laboratory guidance says a normal IGF-1 cannot exclude deficiency and dynamic testing is often required.
- A glucagon stimulation visit may involve fasting and several hours of blood samples. Follow the exact hospital instructions.
AU Australia
Ask for a risk-based endocrine assessment. A GP can review the medical reason for testing and refer to an endocrinologist for supervised testing and treatment decisions.
- See a GP with the pituitary, brain-injury, radiation, surgery, childhood growth, and earlier hormone records.
- An endocrinologist decides whether IGF-1, stimulation testing, other pituitary hormones, or imaging is needed.
- Australia's PBS Growth Hormone Program uses separate adult and child eligibility rules for subsidized treatment.
Safety
Show how it affects daily life
- For a child, plot accurate height measurements over time. One short measurement cannot show whether growth has slowed.
- For an adult, name one regular task that got harder, such as climbing stairs, carrying groceries, finishing a work task, or recovering after ordinary activity.
- Record changes in strength, exercise ability, waist size, fractures, or falls without treating them as proof of growth hormone deficiency.
- Check whether nutrition, a medicine change, or treatment for sleep, thyroid, anemia, or depression affects the fatigue or trouble thinking.
Source checked
Sources behind this handout.
- 01
Molitch ME et al. Evaluation and Treatment of Adult Growth Hormone Deficiency. Endocrine Society Clinical Practice Guideline. 2011.
Source - 02
Fleseriu M et al. Hormonal Replacement in Hypopituitarism in Adults. Endocrine Society Clinical Practice Guideline. 2016.
Source - 03
Endocrine Society. Growth Hormone Deficiency: causes, signs, testing, and treatment. Updated January 24, 2022.
Source - 04
Aversa LS et al. A 2024 Update on Growth Hormone Deficiency Syndrome in Adults: From Guidelines to Real Life. Journal of Clinical Medicine. 2024. PMID: 39458028.
Source - 05
Arlien-Søborg MC et al. Consensus and controversies about diagnosing GH deficiency: a Delphi survey by the GH Research Society. Pituitary. 2025. PMID: 40335774.
Source - 06
pubmed.ncbi.nlm.nih.gov/31760824
Source - 07
pubmed.ncbi.nlm.nih.gov/19773395
Source