Hypopituitarism is loss of function in an endocrine gland due to failure of the pituitary gland to secrete hormones that stimulate that gland's function.The pituitary gland is located at the base of the brain. Patients diagnosed with hypopituitarism may be deficient in one single hormone, several hormones,or have complete pituitary failure.

The pituitary is a pea-sized gland located at the base of the brain, and surrounded by bone. The hypothalamus, another endocrine organ in the brain, controls the function of the pituitary gland by providing "hormonal orders." In turn, the pituitary gland regulates the many hormones that control various functions and organs within the body. The posterior pituitary acts as a sort of storage area for the hypothalamus and passes on hormones that control functionof the muscles and kidneys. The anterior pituitary produces its own hormoneswhich help to regulate several endocrine functions.

In hypopituitarism, something interferes with the production and release of these hormones, thus affecting the function of the target gland. Commonly affected hormones may include:

Gonadotropin deficiency, which involves two distinct hormones affecting the reproductive system. Luteinizing hormone (LH) stimulates the testes inmen and the ovaries in women. This deficiency can affect fertility in men andwomen and menstruation in women. Follicle-stimulating hormone (FSH) has similar effects to LH.

Thyroid stimulating hormone (TSH) is involved in stimulation of the thyroid gland. A lack of stimulation in the gland leads to hypothyroidism.

Also known as corticotropin, adrenocorticotopic hormone (ACTH) stimulates theadrenal gland to produce a hormone similar to cortisone, called cortisol. The loss of this hormone can lead to serious problems.

Growth hormone (GH) regulates the body's growth. Patients who lose supply ofthis hormone before physical maturity will suffer impaired growth. Loss of the hormone can also affect adults.

Other important hormones include prolactin, which stimulates the female breast to produce milk; antidiuretic hormone (ADH), which controls the function ofthe kidneys and, when deficient, can lead to diabetes insipidus. However, patients with hypopituitarism rarely suffer ADH deficiency, unless the hypopituitarism is the result of hypothalamus disease.

However, deficiency of a single pituitary hormone occurs less commonly than deficiency of more than one hormone. Sometimes referred to as progressive pituitary hormone deficiency or partial hypopituitarism, there is usually a predictable order of hormone loss. Generally, growth hormone is lost first, then luteinizing hormone deficiency follows. The loss of follicle-stimulating hormone, thyroid stimulating hormone and adrenocorticotopic hormones follow much later. The progressive loss of pituitary hormone secretion is usually a slow process, which can occur over a period of months or years. Hypopituitarism does occasionally start suddenly with rapid onset of symptoms.

Sometimes, all hormones released by the anterior pituitary will be lost, a condition called panhypopituitarism, or complete pituitary failure.

Hypopituitarism can result from the decreased release of hypothalmic hormonesthat stimulated pituitary function, from the interference of tumors, inflammation, infection, or interrupted blood supply, or from the damage to the pituitary stalk or destruction of the pituitary cells themselves by tumor or disease.

Symptoms of hypopituitarism vary with the affected hormones and severity of deficiency. Frequently, patients have had years of symptoms that were nonspecific until a major illness occurred. Overall symptoms may include fatigue, sensitivity to cold, weakness, decreased appetite, weight loss and abdominal pain. Low blood pressure, headache and visual disturbances are other associated symptoms.

Gonadotrophin deficiency may show up as infertility in women and men. Women may also have decreased interest in sex, premature cessation of menstruation,hot flashes, vaginal dryness and pain during intercourse. Men may also suffersexual dysfunction.

A deficiency of TSH may first be indicated by intolerance to cold, fatigue, weight gain, constipation and pale, waxy, dry skin.

Symptoms of ACTH deficiency include fatigue, weakness, weight loss and low blood pressure.

In children, growth hormone deficiency will result in short stature and growth retardation.

Once the diagnosis of a single hormone deficiency is made, it is strongly recommended that tests for other hormone deficiencies be conducted.

Treatment varies, depending on the age and sex of the patient, severity of the deficiency, the number of hormones involved, and even the underlying causeof the hypopituitarism. Immediate hormone replacement is generally administered to replace the specific deficient hormone. Patients need to be tauch abouthow to manage the impact of their hormone deficiency on daily life. For instance, certain illnesses, accidents or surgical procedures may have adverse complications due to hypopituitarism.

The treatment of hypopituitarism is usually very straightforward, but must normally continue for the remainder of the patient's life. If the cause of thedisorder is a tumor or lesion, radiation or surgical removal are treatment options. Successful removal may reverse the hypopituitarism. However, even after removal of the mass, hormone replacement therapy may still be necessary.

Most patients with hypopituitarism live normal lives as long as therapy is continued. However, hypopituitarism is usually a permanent condition and prognosis depends on the primary cause of the disorder. It can be potentially lifethreatening, particularly when acute hypopituitarism occurs as a result of alarge pituitary tumor. The number of people who die from this disease has increased, and, although the cause is not known, may be due to overtreatment with hormones. Recovery of pituitary function is preferred to lifelong hormone therapy.

There is no known prevention of hypopituitarism, except for prevention of damage to the pituitary/hypothalamic area from injury.

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