GH (Growth Hormone; Somatotropin) is a polypeptide hormone that regulates somatic growth and metabolism through interactions with Growth Hormone R/GHR. GH is released from the anterior pituitary in response to GH-releasing Hormone (GHRH) and Ghrelin, while its secretion is suppressed by Somatostatin. GH levels may also be regulated by Thyrotropin-releasing Hormone, Leptin, Galanin, Neuropeptide Y, and Cortisol. GH can circulate in complex with a shed soluble form of GHR known as GHBP. In addition to promoting bone and muscle mass, GH exerts immunomodulatory effects and induces lipolysis, lactation, amino acid uptake, and protein synthesis. Overproduction of GH can lead to acromegaly, a disorder characterized by enlargement of the hands, feet, and facial features, as well as enhanced risk of cardiovascular disease, respiratory disease, and malignancy. GH deficiency in adults may lead to increases in cardiovascular risk, body fat, and insulin sensitivity, as well as decreased muscle mass and bone density.