HGH refers to human growth hormone and is also a short form for human GH (Somatotropin) taken from human pituitary glands. A protein produced in the pituitary gland which excites the liver to generate somatomedins, it encourages growth of bone and muscle. HGH remains in the bloodstream for simply a few minutes. However, this is sufficient to inspire its uptake by the liver, generating the creation of Insulin-like growth factor-1. This ingredient is the most plentiful hormone formed by the pituitary gland in the brain. HGH peaks during the rapid-growth phase of adolescence, then progressively declines with age.