Human growth hormone (hGH) is a peptide hormone produced by the body. hGH stimulates cell division and cell growth and therefore has an anabolic (muscle-building) effect. Its improper abuse for doping purposes is prohibited.

Growth hormones have a direct and an indirect effect: On the one hand, hGH has a direct effect on blood sugar level and promotes the destruction of fat cells. On the other hand, hGH acts indirectly by binding to somatotropin receptors, which stimulates the production of the protein insulin-like growth factor 1 (IGF-1), particularly in the liver. IGF-1 released into the bloodstream binds to IGF-1 receptors, which are present in nearly all tissues, and controls the expression (production) of numerous other proteins. By these mechanisms, hGH stimulates cell division and cell growth and deploys its tissue-building (anabolic) and regeneration-promoting effect. In adolescents, it promotes the longitudinal growth of the long bones.

The body produces its own hGH in the pituitary gland. It is released into the bloodstream, distributed throughout the body and binds to somatotropin receptors. Somatotropin receptors are produced predominantly in the skeletal muscles and the liver. Additionally administered hGH also binds to these receptors.

Stimulated by supplemented hGH, the liver produces increased amounts of the protein insulin-like growth factor 1 (IGF-1) and releases it into the bloodstream.

IGF-1 binds to IGF-1 receptors, which are present in nearly all tissues, stimulates cell division and cell growth and thus has an anabolic effect. In addition, hGH raises blood sugar levels and promotes the destruction of fat cells.

⬆ Cell division

⬆ Cell growth

⬆ Blood sugar level

⬆ Fat reduction

Exogenous administration of hGH inhibits the body's own growth hormone production via the hypothalamic-pituitary axis. This effect is called negative feedback.

hGH may stimulate growth in internal organs (e.g. heart, liver) and cause severe damage to them. Enlargement of the heart and excessive blood pressure may trigger a heart attack. Additionally, hGH causes disproportional growth of the hands and feet, but also of the chin, nose and ears (acromegaly). These alterations are irreversible. Another possible consequence of hGH abuse is cancer of the colon. Moreover, the alteration of glucose metabolism by hGH entails the risk of triggering diabetes.

Recent studies indicate that growth hormones have a performance-enhancing effect on the power of sprinters. Growth hormones also have a high potential of abuse in all strength and endurance disciplines. To date, about a dozen proven cases of hGH doping have emerged worldwide (e.g. Terry Newton, Patrik Sinkewitz, Inna Eftimova, Anders Veerpalu), and there are clear indications (from confessions, reports and raids) that growth hormones are widely used in sport.

Abuse of hGH is known in cycling, athletics, cross-country skiing and in Paralympic weightlifting and is suspected in swimming and various team sports. Particularly extensive abuse occurs among professional body builders, who serve as role models for many fitness athletes. For this reason, and because hGH is readily available through internet retailers, it has found its way into the mass sports sector.