GH

Growth hormone (GH), also known as somatotropin, is a protein hormone produced and secreted by the pituitary gland, a small gland at the base of the brain. Controlled by the hypothalamus, GH plays a crucial role in metabolism and growth throughout a person's life. 

Having lower-than-normal levels of HGH is called growth hormone deficiency. It’s usually due to an issue with or damage to your pituitary gland that results in hypopituitarism — when one, several or all of the hormones your pituitary gland makes are deficient. Human growth hormone could be one of the affected hormones.