Human growth hormone (hGH) is a hormone that is synthesized and secreted by cells in the anterior pituitary gland located at the base of the brain. hGH is known to act on many aspects of cellular metabolism and is also necessary for skeletal growth in humans. The major role of hGH in body growth is to stimulate the liver and other tissues to secrete insulin-like growth factor (IGF-1). IGF-1 stimulates production of cartilage cells, resulting in bone growth, and also plays a key role in muscle and organ growth.