The pituitary gland sits in a small, bony cavity just underneath the brain. It is attached to the brain by the pituitary stalk, or infundibulum. The pituitary gland sits just below the optic nerves, that take visual impulses from the retina of the eye to the occipital lobe of the brain. The pituitary gland is composed of the anterior lobe and the posterior lobe. The anterior lobe is responsible for producing six hormones. They include prolactin (stimulate the production of breast milk), growth hormone (regulate growth and metabolism), thyroid stimulating hormone (control metabolism through the thyroid gland), ACTH (control the function of the adrenal glands and production of cortisol) and gonadotropin releasing hormones (control the function of the ovaries and testicles). The posterior lobe of the pituitary gland produces oxytocin (stimulate breast milk release and uterine contraction in childbirth) and antidiuretic hormone (controls the reabsorption of water from the kidneys). Abnormal growths in the pituitary gland usually come from one of the cells of the anterior pituitary. Occasionally, Craniopharyngiomas can develop in the pituitary gland. These are developmental rests of cells that have been trapped in the wrong are during development and may gradually enlarge. Tumors of the linings of the brain, meningiomas, can also grow into the region of the pituitary. Occasionally, metastatic tumors can be deposited in the pituitary from another site of cancer.
Causes of Pituitary Tumor
Unknown, but some types may be genetic.
Signs and Symptoms of Pituitary Tumor
Endocrine tumors of the pituitary usually arise from cells that produce prolactin, growth hormone or cortisol. They may produce symptoms by producing excessive quantities of these hormones. Prolactin can cause breast milk secretion. It frequently leads to irregular menstrual periods in women and infertility. Growth hormone secreting tumors that arise before the end of puberty produce gigantism. Adults that develop growth hormone tumors develop acromegaly. This leads to enlargement of the hands, feet and forehead. The tongue may be increased in size. Diabetes may also develop. Cortisol secretion tumors produce Cushing's disease. The face becomes round and moon-like. Excess hair develops. Stretch marks develop. Easy bruising occurs. Menstrual irregularities develop in women and erectile dysfunction in men. Osteoporosis and unexpected fractures may occur. Muscle weakness develops. Craniopharyngiomas often occur in childhood and lead to sexual retardation. There may be problems with hypopituitarism. Meningiomas can secondarily compress and damage the pituitary producing various degrees of hypopituitarism. Similar changes can occur with metastatic tumors of the pituitary gland. As the tumors enlarge, they can compress the optic nerves. This leads to visual loss, usually most prominent in the peripheral visual fields. Blurred vision, double vision, and drooping eyelids can be caused by tumors putting pressure on nerves to the eye or the muscles that move the eye. Headache can occur. Nausea and vomiting may develop. Occasionally, destruction of the skull base can produce cerebrospinal fluid leaks, with clear fluid draining out of the nose or down the throat. Excessive urine output can occur leading to lightheadedness, rapid heart beat and increased thirst.
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Medical Content Last Updated on 07/12/2008
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