3D molecular model of human growth hormone, a peptide hormone secreted by the pituitary gland. The anabolic effects of GH include growth of internal organs, increased muscle mass, bone growth and stimulation of the immune system. However, excessive amounts of GH can result in conditions such as acromegaly and pituitary gigantism. Doses may be given to treat those with GH deficiencies often caused by genetic or congenital disorders.