Growth Hormone Stimulation Test Interpreter (GH Deficiency)
Growth Hormone Stimulation Test Interpreter (GH Deficiency)
Read a peak growth hormone from a glucagon, macimorelin, insulin tolerance, arginine or GHRH-plus-arginine test against the cut-off that belongs to that test, that body weight and that age group. Adult cut-offs follow the 2019 AACE guideline; children are read against both paediatric cut-offs in use, because the Pediatric Endocrine Society declines to choose one.
GH stimulation test
Peak GH + test + BMI + age → verdictAdult, glucagon stimulation test, BMI 25–30, low pre-test probability, peak GH 2.1 µg/L
Adult and transition cut-offs
| Test | Peak GH indicating deficiency | Source | Status |
|---|---|---|---|
| Glucagon — BMI under 25 | 3 µg/L or below | AACE 2019 R22 | Recommended |
| Glucagon — BMI 25–30, high pre-test probability | 3 µg/L or below | AACE 2019 R22 | Recommended |
| Glucagon — BMI 25–30, low pre-test probability | 1 µg/L or below | AACE 2019 R22 | Recommended |
| Glucagon — BMI over 30 | 1 µg/L or below | AACE 2019 R22 | Recommended |
| Macimorelin | 2.8 µg/L or below | AACE 2019 R23 | Recommended; BMI adjustment uncertain |
| Insulin tolerance test | 5 µg/L or below (AACE); below 3 µg/L (Endocrine Society, GRS) | AACE 2019 R21; Endocrine Society 2011 | Reference test; see the ITT page |
| Arginine alone | 0.4 µg/L or below | Endocrine Society 2011 | Not recommended by AACE 2019 (R25) |
| GHRH plus arginine | Below 11 / 8 / 4 µg/L for BMI under 25 / 25–30 / over 30 | Endocrine Society 2011 | Not recommended by AACE 2019 (R25); GHRH unavailable in the US |
Children
| Question | Answer | Source |
|---|---|---|
| Pass mark | Not set: the threshold separating normal from partial deficiency has not been well established | PES 2016 |
| Cut-offs in use | 10 µg/L traditionally; 7 µg/L proposed with standardised assays | Yuen 2023 review |
| Sex steroid priming | Suggested before testing prepubertal boys over 11 and girls over 10 | PES 2016, 2.2.3 |
| Sole criterion? | No — recommend against relying on stimulation results alone | PES 2016, 2.2.1 |
| Assays | Harmonised against IS 98/574, 22 kDa rhGH | PES 2016, 2.2.2 |
One hormone, five tests, many cut-offs
Growth hormone deficiency is diagnosed by provoking the pituitary and measuring the peak. The difficulty is that each stimulus produces a different size of response, body weight blunts all of them, children respond more than adults, and assays disagree — so there is no single number that means deficient. The cut-off belongs to the test, the patient’s weight, the age group and the assay together, and applying one test’s number to another’s result is the commonest way these tests are misread.
The insulin tolerance test remains the reference, but it depends on achieving hypoglycaemia and has absolute contraindications; the insulin tolerance test interpreter handles its glucose gate and its cortisol arm. This page covers the alternatives. The glucagon stimulation test is now the most widely used in adults, and the 2019 AACE guideline gives it a weight-dependent cut-point: 3 µg/L for normal-weight patients and overweight patients with a high pre-test probability, 1 µg/L for obese patients and overweight patients with a low one. Macimorelin, an oral ghrelin agonist, has an approved cut-point of 2.8 µg/L. Arginine alone and GHRH plus arginine appear in the 2011 Endocrine Society guideline with their own cut-offs, but AACE 2019 recommends against both, and GHRH is not available in the United States. Their older cut-offs are shown here only so that historical results can be read.
Children are different. Paediatric cut-offs are several times higher, and the 2016 Pediatric Endocrine Society guideline deliberately declines to set one: it recommends against using a stimulation result as the sole criterion, suggests sex steroid priming in prepubertal children approaching puberty, and asks for harmonised assays. The traditional cut-off is 10 µg/L and some now use 7 µg/L. Rather than choose, this page shows which side of each a result falls on.
Before testing an adult, remember that stimulation testing is not always needed. With three or more other pituitary hormone deficiencies and a low IGF-1, AACE 2019 accepts the diagnosis without it. IGF-1 on its own is a poor test for deficiency, because a normal IGF-1 does not exclude it; the IGF-1 interpreter covers IGF-1 in excess. Units are converted on the growth hormone unit converter.
Frequently asked questions
What is the glucagon stimulation test cut-off for adult GH deficiency?
AACE 2019 uses a peak GH of 3 µg/L for patients with a BMI under 25, and for those with a BMI of 25 to 30 and a high pre-test probability; and 1 µg/L for those with a BMI over 30, and for those with a BMI of 25 to 30 and a low pre-test probability. A peak at or below the applicable cut-point indicates deficiency.
What is the macimorelin test cut-off?
A peak GH of 2.8 µg/L or below indicates adult GH deficiency (AACE 2019). Macimorelin is taken by mouth, does not cause hypoglycaemia, and the guideline notes that BMI-adjusted cut-points for it are uncertain.
What is a normal GH stimulation test result in a child?
There is no agreed pass mark. The traditional cut-off is 10 µg/L, and some centres use 7 µg/L with modern standardised assays. The 2016 Pediatric Endocrine Society guideline declines to set a threshold, recommends against relying on the test result alone, and suggests sex steroid priming in prepubertal boys over 11 and girls over 10.
Why are adult GH cut-offs lower in obesity?
Obesity blunts stimulated GH secretion in people with normal pituitary function, so a cut-off designed for lean patients would label many obese people as deficient. AACE 2019 lowers the glucagon test cut-point to 1 µg/L in obesity, and in overweight patients with a low pre-test probability.
Is the arginine test still used for GH deficiency?
It is still performed in some centres, but AACE 2019 recommends against arginine alone and GHRH plus arginine, describing them as not systematically validated and of low sensitivity and specificity. The older Endocrine Society cut-offs are shown on this page so historical results can be interpreted.
Related calculators
References
- Yuen KCJ, Biller BMK, Radovick S, et al. American Association of Clinical Endocrinologists and American College of Endocrinology guidelines for management of growth hormone deficiency in adults and patients transitioning from pediatric to adult care. Endocr Pract. 2019;25(11):1191–1232. — ITT cut-point 5 µg/L (R21); glucagon 3 µg/L in BMI under 25, and 25–30 with high pre-test probability, 1 µg/L in BMI over 30, and 25–30 with low pre-test probability (R22); macimorelin 2.8 µg/L (R23); transition cut-offs as for adults (R24); arginine and GHRH plus arginine not recommended (R25); no testing needed with 3 or more pituitary deficits and a low IGF-1 (R10).
- Grimberg A, DiVall SA, Polychronakos C, et al. Guidelines for growth hormone and insulin-like growth factor-I treatment in children and adolescents: growth hormone deficiency, idiopathic short stature, and primary insulin-like growth factor-I deficiency. Horm Res Paediatr. 2016;86(6):361–397. — recommend against GH test results as the sole criterion (2.2.1); harmonised assays against IS 98/574 (2.2.2); sex steroid priming in prepubertal boys over 11 and girls over 10 (2.2.3); no well-established threshold separating normal from partial deficiency.
- Yuen KCJ, Johannsson G, Ho KKY, Miller BS, Bergada I, Rogol AD. Diagnosis and testing for growth hormone deficiency across the ages: a global view of the accuracy, caveats, and cut-offs for diagnosis. Endocr Connect. 2023;12(7):e220504. — the paediatric cut-off traditionally 10 µg/L, proposed by some to be lowered to 7 µg/L with standardised assays; assays differ up to 2.5-fold.
- Molitch ME, Clemmons DR, Malozowski S, Merriam GR, Vance ML. Evaluation and treatment of adult growth hormone deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2011;96(6):1587–1609. — the older BMI-specific GHRH plus arginine cut-offs (11, 8 and 4 µg/L) and the arginine-alone 0.4 µg/L criterion, taken as tabulated in Yuen 2023; the 2011 text itself was not re-read for this page.
Not medical advice. For healthcare professionals and education. Reference intervals vary by laboratory and assay — always use your own laboratory's. Never base a dose or a treatment decision on this page alone. Full disclaimer at calcengines.com/disclaimer/