Pituitary Failure (Hypopituitarism) is loss or under functioning of the pituitary gland in which one or more pituitary hormones are deficient.
Hypopituitarism refers to under-function of the pituitary gland. The term refers to both anterior and posterior pituitary gland dysfunction. It may be temporary or permanent. Panhypopituitarism refers to complete loss of all pituitary function. Patients with pan-hypopituitarism should carry a Medic Alert bracelet at all times to notify health care personnel of this problem in case of an emergency.
At the Pacific Pituitary Disorders Center we have one of the world’s largest and most extensive experiences in diagnosing and treating patients with hypopituitarism. Our team of pituitary endocrinologists and neurosurgeons work closely together to preserve or restore pituitary gland function and quality of life, whether it is from from a pituitary adenoma, a brain tumor, hypophysitis, pituitary surgery, radiation treatment or a traumatic brain injury.
Loss of pituitary function can result from damage to the pituitary gland, the pituitary stalk or the hypothalamus. The hypothalamus contains releasing and inhibitory hormones that control the pituitary and reach the gland via the pituitary stalk (infundibulum). Injury to the pituitary gland, pituitary stalk or hypothalamus can occur from a pituitary tumor or brain tumor, brain or pituitary surgery, radiation to the pituitary, pituitary apoplexy (hemorrhage), pituitary inflammation (hypophysitis) and head injury.
There appears to be a somewhat predictable loss of hormonal function: the growth hormone (GH), luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secreting cells appear most vulnerable while thyroid stimulating (TSH) and adrenocorticotropic hormone (ACTH) secreting cells are less vulnerable.
Based on our large surgical experience published in 2008 of over 400 patients treated with endonasal pituitary adenoma removal, gland recovery and loss of function can be reliably predicted. Approximately 50% of patients will have some recovery of pituitary function after adenoma removal, 45% will have no change in function, and 5% will have diminished pituitary function. The most important factor in loss of function was tumor size: for endocrine inactive adenomas, 3 cm or greater in diamter, 2-3 cm in diameter, or under 2 cm in diamter, gland function loss was approximately 14, 7% and 0%, respectively.
Adrenocorticotropic hormone deficiency is a form of adrenal insufficiency that results in decreased cortisol production by the adrenal glands and can be serious and life-threatening. With gradual onset of deficiency over days or weeks, symptoms may include weight loss, fatigue, weakness, depression, apathy, nausea, vomiting and loss of appetite. As ACTH deficiency becomes more severe or has a more rapid onset, (Addisonian crisis) symptoms may include confusion, stupor, psychosis, serum electrolyte changes (low serum sodium and/or elevated serum potassium), vascular collapse, shock and death.
Treatment consists of glucocorticoids (hydrocortisone, dexamethasone or prednisone). For patients with acute adrenal insufficiency (Addisonian crisis), rapid intravenous administration of high dose steroids is essential.
Thyroid stimulating hormone deficiency causes decreased energy, increased need to sleep, cold intolerance, dry skin, constipation, muscle aches and decreased mental capacity. This is a very serious and disabling hormonal deficiency that often causes patients with pituitary disease to seek medical attention.
Treatment with thyroxin (Synthroid) reverses the symptoms and signs over days or weeks and requires careful monitoring of free T4 or total T4 (thyroid function levels).
Women with hypogonadism develop ovarian suppression, menstrual irregularities or absence of periods (amenorrhea), infertility, decreased libido, decreased vaginal secretions and osteoporosis. Blood levels of estradiol decrease and can be replaced as oral Premarin or estrace, or given as a patch applied twice weekly.
Women on estrogen also need progesterone. Men with hypogonadism develop decreased libido, impotence, decreased ejaculate volume, loss of body and facial hair, weakness, fatigue and often anemia. Blood testosterone levels are low and should be replaced as a daily patch or gel or as an injection every 2-3 weeks.
Growth hormone is necessary in children for growth, and in adults to maintain body composition, muscle mass, energy level, cardiovascular status and possibly some mental functions. Symptoms of GH deficiency in adults include fatigue, poor exercise tolerance, decreased muscle mass, increased fat mass and poor quality life. GH is given daily in an injectable form only.
Patients with diabetes insipidus (DI) lack sufficient antidiuretic hormone (ADH, also known as vasopressin) which is made in the hypothalamus and stored in the posterior pituitary gland. DI typically occurs when the posterior pituitary gland, pituitary stalk or hypothalamus are manipulated or injured during surgery or impacted by a brain tumor, a traumatic brain injury or inflammation of the pituitary gland or stalk. This lack of ADH causes an inability to concentrate urine at the kidney with resultant copious and dilute urine and excessive thirst. Such patients can become rapidly dehydrated unless they are given access to water or other fluids or the ADH is replaced (as DDAVP).
DI may occur transiently in up to 25% of patients after transsphenoidal pituitary adenoma surgery but is typically only transient (lasting for 1 to several days) but is permanent in 1-3% of patients after pituitary adenoma surgery. In contrast it is seen in many patients with a craniopharyngioma both before and more often after surgery (in up to 40-50% of patients) as these tumors typically arise along the pituitary stalk.
Replacement of ADH resolves the high urine output of DI. Treatment with DDAVP (a synthetic type of ADH) can be given by subcutaneous injection, intranasal spray, or a tablet, typically taken once or twice a day. Use of DDAVP should be carefully monitored by an endocrinologist.