Underactive Pituitary Gland (Hypopituitarism)

Written by Gretchen Holm | Published on July 23, 2012
Medically Reviewed by George Krucik, MD

What Is an Underactive Pituitary Gland?

Your pituitary gland is located just below your brain. It releases eight hormones that each plays its own role in your body processes. Functions range from stimulating bone growth to prompting your thyroid gland to release hormones that control your metabolism.

Hormones produced by the pituitary gland include:

  • adrenocorticotropic hormone (ACTH)
  • antidiuretic hormone (ADH)
  • follicle-stimulating hormone (FSH)
  • growth hormone
  • luteinizing hormone (LH)
  • oxytocin
  • prolactin
  • thyroid-stimulating hormone (TSH)

Sometimes, your pituitary gland does not release enough of one or more of these hormones. This underactivity is called hypopituitarism.

What Causes an Underactive Pituitary Gland?

Your pituitary gland may stop producing enough of one or more of its hormones if it has suffered trauma. For example, if you have had brain surgery, a brain infection, or a head injury, your pituitary gland may be affected.

Certain tumors can also affect the function of this gland. These include:

  • brain tumors
  • pituitary gland tumors (a common cause of hypopituitarism)
  • hypothalamus tumors

Other possible causes of hypopituitarism include:

  • sarcoidosis (a chronic lung disease)
  • hemochromatosis (a hereditary disease characterized by too much iron in the body)
  • histiocytosis X (a rare autoimmune disorder; immune cells attack the organs)
  • stroke
  • tuberculosis
  • lymphocytic hypophysitis (an autoimmune disease characterized by inflammation of the pituitary gland)
  • blood loss during childbirth (Sheehan syndrome)
  • radiation treatments

Sometimes, doctors can’t figure out what caused a particular case of hypopituitarism.

What Are the Symptoms of an Underactive Pituitary Gland?

The symptoms of hypopituitarism depend on which hormones your pituitary gland is not producing enough of. For example, if the pituitary does not produce enough growth hormone in a child, he or she may have a permanently short stature. Alternately, if it doesn’t produce enough follicle-stimulating hormone or luteinizing hormone, it might cause problems with sexual function, menstruation, and fertility.

In some cases, you may not have any symptoms at all. For example, if you are an adult and your pituitary gland does not produce enough growth hormone, you will probably not notice because you have already finished growing. In children, however, this condition is far more noticeable.

How Is an Underactive Pituitary Gland Diagnosed?

If your doctor thinks you may have hypopituitarism, he or she will use a blood test to check your levels of the hormones produced by the pituitary gland. Sometimes, he or she will also check for hormones that your pituitary gland stimulates other glands to release.

For example, your doctor may check your T4 levels. Your pituitary gland doesn’t produce this hormone. However, it releases TSH, which stimulates your thyroid gland to release T4. Therefore, having low levels of T4 indicates that you may have a problem with your pituitary gland.

Your doctor may prescribe specific medications before doing blood tests. These medications are designed to stimulate your body’s production of specific hormones. Taking these before the test can help your doctor get a better understanding of your pituitary gland function.

Once your doctor has determined which hormone levels are low, he or she must check the parts of your body (target organs) affected by those hormones. Sometimes, the problem isn’t with your pituitary gland itself, but rather with these other target organs.

Your doctor may also perform imaging tests, such as a computed tomography (CT) scan or magnetic resonance imaging (MRI) scan on your brain. These can help him or her figure out if a tumor on your pituitary gland is affecting its function.

How Is an Underactive Pituitary Gland Treated?

There is no single course of treatment for this condition because a number of hormones may be affected. In general, the goal of treatment is to bring all your hormone levels back to normal.

This may involve taking medications to replace the hormones your pituitary gland is not producing properly. In this case, your hormone levels will need to be checked regularly. This allows your doctor to adjust the doses of medications you are taking to make sure you’re getting the amount you need.

If your pituitary problems are caused by a tumor, surgery to remove the tumor may restore your hormone production to normal. In some cases, eliminating a tumor will also involve radiation therapy.

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