Definition

The pituitary gland is in the brain. It produces several important hormones that control the production of other hormones made by glands in the body.

The pituitary gland is responsible for many body functions, including the following:

• Growth
• Blood pressure
• Sex organ function
• Thyroid gland function
• Breast milk production and other aspects of pregnancy and birth
• Water balance in the body
• Some reactions to stress

Hypopituitarism is an insufficient production of one or more hormones. A problem in the pituitary can cause the amount of hormones from other glands to diminish as well.

Causes

There are several factors which may cause this condition:

• Tumors of the pituitary gland, hypothalamus, or brain
• Poor blood supply to the pituitary gland
• Head trauma
• Radiation therapy to pituitary gland, head, or neck
• Stroke
• Infections and inflammatory diseases
• Uncommon immune system or metabolic diseases
• A rare complication after pregnancy, called Sheehan’s syndrome
• Metastatic cancer from lung, colon, prostate, or melanoma

Risk Factors

Factors that may increase your the chance for hypopituitarism include:

• History of childhood cancer—some treatments can damage the pituitary
• Infections
• Genetics
• Type 1 diabetes
• Sickle cell anemia
• Reduced blood volume or hypovolemia

Symptoms

Compression of the tumor on local structures, especially the nerves of the eyes, can cause:

• Blurred vision
• Loss of visual field
• Poor temperature control

Symptoms often begin gradually and are not specific since hormones control a variety of body functions. They may not be recognized for a while. Specific symptoms will depend on the type and level of hormone affected. For example:

• Growth hormone deficiency:
  • Poor overall growth
  • Short stature
  • Obesity
  • Muscle weakness
• Thyroid-stimulating hormone deficiency:
  • Sensitivity to cold
  • Weight gain
  • Constipation
  • Hair that is brittle and coarse
  • Slow heart rate
  • Dry skin
  • Muscle weakness or fatigue
• Adrenocorticotropic hormone (ACTH) deficiency:
  • Fatigue and weakness
  • Weight loss
  • Decrease in skin pigmentation
  • The absence of a menstrual period in women of reproductive age
• Follicle-stimulating hormone and luteinizing hormone deficiency:
  • Infertility in men and women
  • Vaginal dryness
  • Loss of some gender-specific sexual characteristics—women may lose hair from their underarms, body, and pubic area
  • Reduced interest in sex
  • The absence of a menstrual period in women of reproductive age
  • Difficulty maintaining an erection
  • Muscle weakness
  • Small testes
  • Breast enlargement in men—gynecomastia

Diagnosis

You will be asked about your symptoms and medical history. A physical exam will be done. You may be referred to an endocrinologist. This is a type of doctor that focuses on hormone disorders.

Tests to determine hypopituitarism include taking a blood sample to do the following:

• Measure the levels of hormones produced by the pituitary gland
• Measure the levels of hormones produced by target endocrine glands, which are influenced by the pituitary gland

Pituitary function tests may be done such as:

• Growth hormone-releasing hormone (GHRH) test
• Arginine stimulation test
• Clonidine stimulation test
• Insulin tolerance test
• Adrenocorticotropic hormone (ACTH) stimulation test

After the diagnosis is confirmed, imaging tests will be done to identify problems such as tumors or abnormal tissue and growth or shrinkage of the pituitary gland. This can be done with an MRI scan.

Treatment

Talk with your doctor about the best treatment plan for you. This condition is likely permanent, depending on the cause. It will likely need to be treated for life. Treatment options include:

Prevention

In general, this condition is not preventable. Be aware of the risks and symptoms. This will make early diagnosis and treatment possible.

The Pituitary Society http://www.pituitarysociety.org

Thyroid Foundation of Canada http://www.thyroid.ca

Schneider HJ, Aimaretti G , Kreitschmann-Andermahr I, et al. Hypopituitarism. Lancet. 2007;369:1461-1470.

Tomlinson JW. Association between premature mortality and hypopituitarism. West Midlands Prospective Hypopituitary Study Group. Lancet. 2001; 357:425.