Human growth hormone (HGH) is a hormone excreted by the pituitary gland. Although it's excreted in small quantities throughout a person's life, it's excreted in larger quantities at the start of puberty until a person reaches adulthood. For the most part, a person's height depends on their level of HGH during this period.
Too little HGH during the critical growth period leads to hypopituitary dwarfism the body type commonly referred to as a midget - proportions are correct but all the limbs and torso are smaller than normal.
Too much HGH during this period leads to gigantism. People with this condition generally grow to a height of over 7 feet and have an ectomorphic body type with very little musculature or fat. Complications can often result from this growth as stress is put on the legs and feet, which often are not large in cross section to support the person's weight.
The continuous production of HGH into adulthood leads to acromegaly. The patient is usually well over 6 feet tall, but stops growing in height. However, the other bones of the body continue to grow. Weight can continue to increase and the face takes on a distinctive "lantern-jaw" shape.
At present, hypopituitary dwarfism can be treated by giving the patient synthetic HGH during adolescence. Patients still are of below normal height, but generally grow within a normal range of height for persons their age.
Because HGH stimulates the growth of muscle, it's often used by athletes who participate in strength events, such as weightlifting, baseball power-hitting, wrestling and body building. However, it has serious side effect when used in this manner, such as increasing overall body weight and interfering with other hormones in the body that regulate weight.
Persons who have a form of dwarfism are not assisted by HGH as these disorders are not related to the amount of HGH in the body but by how bones in the arms and legs develop.