Pituitary disorders are conditions that affect the ability of the “master gland” of the endocrine system to regulate body functions. Patients with pituitary disorders may experience changes in numerous aspects of bodily functions, including metabolism, sexual development and growth.

The pituitary gland receives signals from the brain and then transmits them to parts of the body using natural chemical messengers called hormones. These hormones travel in the blood and trigger responses from the thyroid gland, adrenal glands, reproductive glands and other tissues. The hormones secreted by the pituitary include:

• Growth hormone (GH). Stimulates bone and muscle growth. Excessive GH can cause acromegaly or gigantism. Insufficient amounts may cause dwarfism.
  
  
• Prolactin (PRL). Stimulates milk production in women after childbirth and influences fertility, bone strength and metabolism. Too much PRL causes hyperprolactinemia, which can induce the production of breast milk both in women who are not breastfeeding and in men.
  
  
• Adrenocorticotropin (ACTH). Stimulates the adrenal glands to maintain blood pressure and glucose levels during times of stress. Excessive ACTH may lead to Cushing’s disease, whereas too little impairs the stress response.
  
  
• Thyroid-stimulating hormone (TSH). Stimulates the thyroid gland to produce hormones that regulate metabolism, growth and nervous system function. Overproduction of TSH is one cause of hyperthyroidism, and underproduction can cause hypothyroidism.
  
  
• Luteinizing hormone (LH) and follicle stimulating hormone (FSH). Stimulate activity in the reproductive glands (ovaries and testes). Too much LH or FSH may cause early puberty in children. Underproduction of these hormones causes central hypogonadism.
  
  
• Antidiuretic hormone (ADH). Reduces the amount of water and sodium excreted from the body and helps control blood pressure. Patients may develop diabetes insipidus when the pituitary gland does not secrete ADH.

Most pituitary disorders are the result of noncancerous tumors (adenomas) that grow in the pituitary gland. When functional, these adenomas produce excess hormones and do not respond to the body’s signals to stop. Adenomas may occur spontaneously or as a result of genetic conditions. Other genetic mutations may limit the ability of the pituitary gland to produce hormones or other tissues to respond. Pituitary disorders may also be caused by damage to the pituitary gland, such as trauma, disease or exposure to radiation.

Blood tests are the key to diagnosing pituitary disorders. Results indicating abnormal levels of hormones in the blood are likely indicators of pituitary disorders. The diagnosis may be confirmed by “challenge” tests that record results after a physician-induced change to the levels. These tests can either stimulate or suppress the release of pituitary hormones. Imaging tests can also confirm the results when they reveal a pituitary adenoma.

Treatment for a pituitary disorder depends on its cause. Surgery is often preferred when an adenoma is producing excess hormones or preventing other pituitary cells from working. Medications may also be used for hormone replacement, to block the overproduction by the pituitary or to block the effects of the hormone. After treatment, patients will likely require lifetime monitoring to detect any further changes in pituitary function.