The Growth Hormone (GH) is secreted by the pituitary gland, an endocrine gland located at the base of the brain, which regulates the activity of almost all the other endocrine glands in the body. GH is produced not only during growth but, to varying degrees, even in adults. During puberty, its predominant effect is on the growth of bones as well as several other tissues in the body, including muscles. This effect on the growth of muscle tissue makes the hormone a drug often used for doping purposes! It is not easy to measure a lack of GH, since hormonal secretion varies both within the same individual and between different individuals. In each child, secretion of GH varies notably throughout the day. The old saying, “You grow while you sleep,” carries an element of truth, because GH levels do rise during the night. A lack of GH causes pituitary dwarfism, characterized by an individual being abnormally short, but otherwise normal when it comes to the proportions between different parts of the body.