What this test measures
Human Growth Hormone (hGH) is secreted in pulses by the anterior pituitary, mostly at night during deep sleep and in response to exercise, stress, hypoglycaemia and meals. It acts directly on tissues and indirectly through hepatic Insulin-like Growth Factor-1 (IGF-1) to drive linear growth in children and to regulate body composition, glucose, lipid and bone metabolism throughout life.
A random hGH value is poorly interpretable because of the pulsatile secretion — levels can swing from < 0.1 ng/mL to > 30 ng/mL within hours in a normal person. For deficiency, dynamic tests (insulin tolerance, glucagon, GHRH-arginine) are required. For excess (acromegaly), a glucose-suppression test (OGTT with GH measurements) is the gold standard. IGF-1 is the practical first-line marker because it integrates 24-hour GH secretion.
Why it matters
GH deficiency in childhood causes short stature and is treated with daily recombinant GH injections. In adults, GH deficiency (usually from pituitary tumour, surgery or radiation) causes central adiposity, reduced muscle mass, fatigue, dyslipidaemia and reduced quality of life — and is also treated with GH replacement.
GH excess causes gigantism in children (before growth plate closure) and acromegaly in adults — enlarged hands and feet, coarsening facial features, sleep apnoea, hypertension, diabetes, cardiomyopathy and a measurably reduced life expectancy. Acromegaly is treatable (surgery, somatostatin analogues, pegvisomant) but is often diagnosed years late because the changes are insidious — IGF-1 plus a glucose-suppression GH is the standard biochemical workup.
How to prepare
A random hGH on its own is rarely ordered — most labs request a specific protocol. For a stimulation or suppression test, follow your endocrinologist's specific instructions (fasting from midnight, no exercise that morning, no acute illness). Stop biotin for 48–72 hours. Continue other medications unless instructed otherwise.
Markers & reference ranges
Reference ranges below are typical adult values. Your lab's reported range may differ slightly based on the assay platform and patient demographics — always read your report against the range printed on it.
| Marker | Normal range | If low | If high |
|---|---|---|---|
| Growth Hormone (ng/mL)[1][2] | Random adult: < 5 (mostly < 1 between pulses) — single value not diagnostic | A low random value does not establish GH deficiency. Deficiency is diagnosed by failure of GH to rise above 5 ng/mL (assay-dependent) on a dynamic stimulation test in someone with consistent clinical and biochemical features. | A random value > 5 ng/mL is not by itself diagnostic of acromegaly. Acromegaly is confirmed by failure of GH to suppress to < 1 ng/mL after a 75 g oral glucose load, plus a raised age-matched IGF-1 and a pituitary MRI. |
GH testing — diagnostic approach
| Question being asked | Best test | Diagnostic cut-off |
|---|---|---|
| Is there GH deficiency in a child? | GH stimulation test (clonidine, glucagon, arginine) | Peak GH < 10 ng/mL (assay-dependent) |
| Is there GH deficiency in an adult? | Insulin tolerance test or glucagon stimulation | Peak GH < 3–5 ng/mL |
| Is there acromegaly? | OGTT with GH measurement + IGF-1 | GH does not suppress < 1 ng/mL; IGF-1 raised |
| Treatment response in acromegaly | IGF-1 + random GH | IGF-1 in age-matched range; GH < 1 ng/mL |
Frequently asked questions
Why is a single random GH not enough to diagnose anything?
GH is secreted in short pulses every 2–3 hours and is undetectable between pulses in healthy people. A single low value can be entirely normal; a single high value can be a normal post-stress peak. Dynamic testing is required for a real diagnosis.
Should I get IGF-1 instead?
For most outpatient evaluations, yes. IGF-1 has a long half-life and integrates 24-hour GH activity — it is the practical screen for both GH deficiency and acromegaly. A normal age-matched IGF-1 makes acromegaly very unlikely.
I want to take growth hormone for anti-ageing or bodybuilding — is that safe?
No. Endocrine Society explicitly advises against GH use for healthy ageing or athletic enhancement. GH abuse causes insulin resistance, fluid retention, carpal tunnel, joint pain, and may raise cardiovascular and cancer risk. GH is also a banned substance in competitive sport.
My child is short — should I check GH first?
No — most short stature in Indian children is familial or due to nutritional and chronic illness factors. A paediatric workup typically starts with height velocity, bone age X-ray, thyroid function, coeliac screen, and IGF-1. GH stimulation is reserved for children whose initial workup raises real concern.
What is acromegaly?
A pituitary tumour secreting excess GH after the growth plates have closed in adulthood. It causes gradual enlargement of the hands, feet and jaw, coarsening facial features, sweating, headaches, joint pain and metabolic complications. Early diagnosis with IGF-1 and OGTT is critical because untreated acromegaly shortens life expectancy.
Does sleep affect GH testing?
GH peaks during deep sleep, so a sleep-deprived patient may have an abnormally low baseline. Outpatient samples are taken in the morning after a normal night's sleep.
Can stress raise the GH level?
Yes — acute stress, exercise and hypoglycaemia all raise GH transiently. Avoid heavy exercise the morning of the test.
Related Hormones / Endocrine tests
Tests commonly ordered alongside HUMAN GROWTH HORMONE (HGH), or that help interpret an unexpected result.
Sources & references
- Endocrine Society — Acromegaly Guideline · accessed 2026-05-30T00:00:00.000Z
- Endocrine Society — Adult GH Deficiency · accessed 2026-05-30T00:00:00.000Z
- NIH MedlinePlus — Growth Hormone Test · accessed 2026-05-30T00:00:00.000Z
- NCBI StatPearls — Growth Hormone · accessed 2026-05-30T00:00:00.000Z
Book with Zelnoo
Get your HUMAN GROWTH HORMONE (HGH) test done at home — transparent prices, NABL-accredited labs.
Zelnoo lets you compare diagnostic test prices across NABL-accredited labs in Mumbai & Thane, book a free home phlebotomist visit, and receive digital reports in 24–48 hours into a consent-first report vault. No subscriptions, no membership fees — pay only for the test you book.
Book HUMAN GROWTH HORMONE (HGH) now