Hypopituitarism

Definition

Hypopituitarism is a condition in which the pituitary gland does not produce normal amounts of some or all of its hormones.

Alternative Names

Pituitary insufficiency

Causes, incidence, and risk factors

The pituitary gland is a small structure that is located just below the brain. It is attached by a stalk to the hypothalamus, the area of the brain that controls its function.

The hormones released by the pituitary gland (and their functions) are:

• Adrenocorticotropic hormone (ACTH) -- stimulates the adrenal gland to release cortisol; cortisol helps to maintain blood pressure and blood sugar
• Antidiuretic hormone (ADH) -- controls water loss by the kidneys
• Follicle stimulating hormone (FSH) -- controls sexual function and fertility in males and females
• Growth hormone (GH) -- stimulates growth of tissues and bone
• Luteinizing hormone (LH) -- controls sexual function and fertility in males and females
• Oxytocin -- stimulates the uterus to contract during labor and the breasts to release milk
• Prolactin -- stimulates female breast development and milk production
• Thyroid stimulating hormone (TSH) -- stimulates the thyroid gland to release hormones that affect the body's metabolism

In hypopituitarism, there is a lack of one or more pituitary hormones. Lack of the hormone leads to loss of function in the gland or organ that it controls. For example, no TSH leads to loss of function in the thyroid gland.

Hypopituitarism may be caused by:

• Brain surgery
• Brain tumor
• Head trauma
• Infections of the brain and the tissues that support the brain
• Radiation
• Stroke
• Subarachnoid hemorrhage (from a burst aneurysm)
• Tumors of the pituitary gland or hypothalamus

Occasionally, hypopituitarism is due to uncommon immune system or metabolic diseases, such as:

• Hemochromatosis
• Histiocytosis X
• Sarcoidosis

Hypopituitarism is also a rare complication after pregnancy, a condition called Sheehan's syndrome.

Symptoms

• Abdominal pain
• Cessation of menstrual periods (in women)
• Decreased appetite
• Decreased sexual interest (in men)
• Failure to release milk (in women)
• Fatigue
• Headache
• Infertility (in women)
• Lack of sex drive (in women)
• Loss of armpit or pubic hair
• Loss of body or facial hair (in men)
• Low blood pressure
• Sensitivity to cold
• Short stature (less than 5 feet) if onset is during a growth period
• Slowed growth and sexual development (in children)
• Visual disturbances
• Weakness
• Weight loss

Note: Symptoms may develop slowly and may vary greatly, depending upon:

• The number of lacking hormones and their target organs
• The severity of the disorder

Other symptoms that may occur with this disease:

• Facial swelling
• Hair loss
• Hoarseness or changing voice
• Joint stiffness
• Weight gain (unintentional)

Signs and tests

To diagnose hypopituitarism, there must be low hormone levels due to a problem with the pituitary gland. The diagnosis must also rule out diseases of the organ that is affected by this hormone.

Tests include:

• Brain CT scan
• Pituitary MRI
• Serum ACTH
• Serum cortisol
• Serum estradiol (estrogen)
• Serum follicle stimulating hormone (FSH)
• Serum insulin-like growth factor 1 (IGF-1)
• Serum luteinizing hormone (LH)
• Serum testosterone level
• Serum thyroid stimulating hormone (TSH)
• Thyroid hormone (T4)

Levels of a pituitary hormone may be high in the bloodstream if you have a pituitary tumor that is producing too much of that hormone. The tumor may crush the rest of the cells of the pituitary, leading to low levels of other hormones.

Treatment

If hypopituitarism is caused by a tumor, you may need surgery to remove the tumor, with or without radiation therapy. It is often necessary to replace hormones that are lacking, even after successful treatment of a pituitary tumor.

Hormone therapy is needed to replace hormones that are no longer made by organs under the control of the pituitary gland. These may include:

• Corticosteroids (cortisol)
• Growth hormone
• Sex hormones (testosterone for men and estrogen for women)
• Thyroid hormone

Drugs are also available to treat related infertility in men and women.

Expectations (prognosis)

Hypopituitarism is usually permanent and requires lifelong treatment. However, you can expect a normal life span.

Complications

Side effects of drug therapy can develop. In severe illness, failing to take extra corticosteroids can be life-threatening.

Calling your health care provider

Call your health care provider if you develop symptoms of hypopituitarism.

Prevention

In most cases, the disorder is not preventable. Awareness of risk may allow early diagnosis and treatment.

References

Melmed S, Kleinberg D. Anterior pituitary. In: Kronenberg H, Melmed S, Polonsky K, Larsen PR, eds. Williams Textbook of Endocrinology. 11th ed. Philadelphia, Pa: Saunders Elsevier; 2008:chap 8.