Hypersecretion of growth hormone (GH) or somatotropin hormone (STH) from adenohypophysis of pituitary gland causes giganrism in children and acromegaly in adulthood. Giganrism involves excessive growth (lengthening) of bones with enlargement of internal organs as well. Acromegaly causes abnormal thickening of bones (due to ossification of periosteum) especially at face and margins of hand and feet.