The endocrine system of the body is composed of glands that secrete hormonal substances into the blood stream. These include the pancreas, ovaries, thyroid and adrenal glands. The pituitary is a large gland belonging to this system. It is located at the base of the skull. Conditions of the pituitary can affect growth, sexual development and body weight. Pituitary tumours are relatively common but diagnosis is often difficult and delayed. Pituitary conditions may be features of a number of different genetic conditions.