Secreted by anterior pituitary.

Function: Stimulates linear growth and muscle mass through IGF-1 (somatomedin C) secretion by liver. ↑ insulin resistance (diabetogenic).- IGF-1 (somatomedin) increases synthesis of cartilage (chondrogenesis)

Regulation: Released in pulses in response to growth-hormone-releasing hormone (GHRH). - Secretion ↑: exercise, deep sleep, puberty, hypoglycemia, ghrelin, amino-acids (eg, arginine). - Secretion ↓: glucose and somatostatin release via negative feedback by somatomedin.

Excess secretion of GH (eg, pituitary adenoma) may cause acromegaly (adults) or gigantism (children). Treat with somatostatin anologs (eg, octreotide) or surgery.