Human Growth Hormone (HGH), also known as somatotropin, is secreted by the anterior lobe of the pituitary gland. It stimulates the growth of essentially all tissues of the body. HGH is synthesized and secreted by anterior pituitary cells called somatotrophs. Young adolescents secrete HGH at the rate of about 700 μg/day, while healthy adults secrete HGH at the rate of about 400 μg/day.