Growth Hormone (GH)
Growth hormone is released in pulses by the anterior pituitary, mainly during deep sleep and in response to exercise, fasting, and stress. It drives linear growth in children and supports protein metabolism, fat breakdown, and glucose regulation in adults. Random GH levels are rarely useful because of pulsatile secretion; stimulation testing (for deficiency) and suppression testing (for excess) are the definitive tests. IGF-1 is the preferred screening test for both.
Reference Ranges
Male
0 – 5
ng/mL
Female
0 – 10
ng/mL
Child
0 – 10
ng/mL
Reference ranges may vary by laboratory. Always compare with the range printed on your lab report.
What Low Levels Mean
A low random GH is not informative on its own because GH levels are normally near zero between pulses. GH deficiency requires stimulation testing — insulin tolerance, glucagon, or macimorelin stimulation. In children with poor linear growth, low stimulated GH plus low IGF-1 confirms deficiency, and GH replacement can be life-changing. In adults, GH deficiency is rarely treated unless there is documented pituitary disease.
What High Levels Mean
A single high GH is also difficult to interpret because of normal peaks during sleep, exercise, stress, and fasting. Glucose-suppressed GH testing (measuring GH after oral glucose) is the standard test for acromegaly — failure to suppress GH below 1 ng/mL is diagnostic. Persistent unsuppressed GH plus elevated IGF-1 confirms acromegaly and prompts pituitary MRI.
Frequently Asked Questions
Why is random GH rarely tested?
GH is released in about 10–20 short pulses per day, mostly during deep sleep, with long periods of near-zero levels between pulses. A random GH measurement can be zero in a healthy person or high in someone fasted or stressed — it does not reliably discriminate disease. Dynamic testing (stimulation for deficiency, suppression for excess) is required.
How is GH deficiency diagnosed in children?
A combination of: growth velocity below expected, height below 2 standard deviations for age, bone age delay, low IGF-1 for age, and failed GH response to two stimulation tests (peak GH below 7–10 ng/mL depending on the stimulus). Pituitary MRI rules out structural causes. Confirmed cases are treated with daily subcutaneous GH injections, typically until puberty is complete.
Is GH used as an anti-aging treatment?
GH declines with age (somatopause), and injectable GH is sometimes marketed as an anti-aging therapy. Major medical societies (Endocrine Society, AACE) strongly oppose this use — benefits are unproven, risks include edema, joint pain, insulin resistance, increased cancer risk, and it is illegal in many countries without a specific medical indication. GH for healthy older adults is not supported by evidence.
Related Hormones tests
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Pancreatic hormone that controls blood sugar.
µIU/mLHormonesHOMA-IR (Insulin Resistance Index)
Calculated index that estimates insulin resistance.
indexHormonesBeta-hCG (Human Chorionic Gonadotropin)
Pregnancy hormone — also a tumor marker for certain cancers.
mIU/mLHormonesSex Hormone Binding Globulin (SHBG)
Protein that binds sex hormones in blood, controlling their availability.
nmol/LThis information is for educational purposes only and should not replace professional medical advice. Always consult your doctor for interpretation of your test results.
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