The pituitary gland is located at the base of the brain and is controlled by a part of the brain named the hypothalamus. The pituitary gland has two parts, a front or anterior part that controls other endocrine glands of the body, and a back or posterior part which is an extention of the brain that secretes anti-diuretic hormone or ADH. The commonest pituitary tumor is one that secretes the hormone prolactin (prolactinoma). Prolactin is a milk producing hormone and often presents as breast soreness and/or leakage of milk from the breasts in a non-pregnant non-breast feeding person (galactorrhea). Menstrual periods are often inhibited also. Most of these tumors are small (micro-adenomas) and can be controlled by medication, but occasionally they become big and need surgical removal. Less commonly, pituitary tumors secrete growth hormone (GH) causing a fleshy overgrowth of the soft tissues of the face and hands. Another developmental tumor is the craniopharyngioma. These can become cystic and grow in size to put pressure on the optic chiasma (visual nerve crossing site) causing loss of vision to the sides of the visual field. They can also destroy the functions of the anterior pituitary, causing growth failure in children from loss of growth hormone (GH), loss of the menstrual cycles, and headaches if the pressure in the brain behind the tumors, builds up. Loss of ADH can lead to an inability to concentrate urine with increased urination and thirst (diabetes insipidis). Replacement of the lost hormones and sometimes surgical removal of these tumors comprise their treatment.