Laboratory Medicine Program

Growth hormone
(Somatotropin, Human Growth Hormone)

Clinical Decription:
Human growth hormone (hGH or somatotropin) is synthesized by the alpha cells of the anterior pituitary gland. hGH secretion is controlled by the hypothalamic growth hormone-releasing hormone (GH-RH) and somatostatin, which stimulates and inhibits release. hGH is secreted episodically (pulsatile secretion) and is modulated by many factors including stress, physical exercise and sleep. During childhood and adolescence, hGH causes the body statural growth and in adults, it affects major metabolic processes that encourages growth. The metabolic effect of hGH can be divided into two main categories: a) anti-insulin direct action (lipolytic and causing hyperglycaemia) b) insulin-like indirect action (anti-lipolytic and mitogenic). Insulin-like growth factor is a somatomedin, which is bound to carrier proteins, so it prolongs the half-lives, therefore, making it a more stable and reliable screening test for growth hormone deficiency and excess. Also, due to marked fluctuation of hGH in daily secretion, a single random specimen has limited clinical interest. A test that would provide more detailed information is the glucose tolerance test or the challenge test with arginin, insulin, glucagon, L-dopa, GH-RH are used to stimulate hGH release. The determination of human growth hormone is useful in the diagnosis of growth disorders such as: 1) Hormone deficiency - Delay puberty and small stature in adolescents 2) Hormone excess - Gigantism in young children or adolescents and acromegaly in adults 3) Evaluation of growth hormone replacement therapy

Method: Chemiluminescent immunoassay (CLIA); Diasorin Liaison XL

Component Tests Used: n/a

Reference Ranges Used:
Female: <10 ug/L Male: <1 ug/L

Specimen Type: serum
Volume: 5 mL (minimum: 5 mL)

Shipping: Frozen at -20C

Special Instructions: Fasting required. Timed samples must be marked clearly. Centrifuge and aliquot sample.

Testing Schedule(s): once a week.

Turnaround Time: 7-10 days

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