Growth hormone (GH) is a peptide hormone secreted by the anterior pituitary. Its main action is to stimulate the production and release of insulin-like growth factor 1 (IGF-1) by the liver. Excessive secretion causes acromegaly, while deficiency causes failure of growth in children and metabolic problems in adults.
The secretion of GH is very episodic, so random measurement is rarely useful diagnostically.
Failure of GH to suppress during a glucose tolerance test is diagnostic for acromegaly.
Stimulation tests, such as an insulin tolerance test (NB. potentially dangerous, should only be carried out in centres experienced in it) or stimulation with arginine, GHRH/arginine or glucagon, can be carried out to test for insufficiency. GH deficiency may occur as part of a more general deficiency of pituitary hormones, so other hormones are often measured at the same time.
Sample Requirements and Reference Ranges
|Minimum volume||2 mL|
Random GH > 10 μg/L excludes GH deficiency
Random GH < 0.4 μg/L excludes acromegaly
Severe Growth Hormone Deficiency
Adults Peak GH during ITT < 3 μg/L
Adults Peak GH with GHRH/Arginine < 5 μg/L
Children Peak GH during provocation < 5 μg/L
Failure to suppress during OGTT < 1 μg/L
Mean integrated 24hr GH > 1.7 μg/L
|Turnaround time||7 days|