Causes

Hypopituitarism has a number of causes. In many cases, hypopituitarism is caused by a tumor of the pituitary gland. As a pituitary tumor increases in size, it can compress and damage pituitary tissue, interfering with hormone production. A tumor can also compress the optic nerves, causing visual disturbances.

In addition to tumors, certain diseases or events that cause damage to the pituitary gland may also trigger hypopituitarism. Examples include:

• Head injuries
• Brain surgery
• Radiation treatment to the head or neck
• Lack of blood flow to the brain or pituitary gland (stroke) or bleeding (hemorrhage) into the brain or pituitary gland
• Certain medications, such as narcotics, high-dose corticosteroids or certain cancer drugs called checkpoint inhibitors
• Inflammation of the pituitary gland caused by an abnormal immune system response (hypophysitis)
• Infections of the brain, such as meningitis, or infections that can spread to the brain, such as tuberculosis or syphilis
• Infiltrative diseases, which affect multiple parts of the body, including sarcoidosis, an inflammatory disease occurring in various organs; Langerhans cell histiocytosis, in which abnormal cells cause scarring in numerous parts of the body; and hemochromatosis, which causes excess iron deposits in the liver and other tissues
• Severe loss of blood during childbirth, which may cause damage to the front part of the pituitary gland (Sheehan's syndrome or postpartum pituitary necrosis)

In some cases, hypopituitarism is caused by a genetic mutation (inherited). These mutations affect the pituitary gland's ability to produce one or more of its hormones, often starting at birth or in early childhood.

Tumors or diseases of the hypothalamus, a portion of the brain situated just above the pituitary, also can cause hypopituitarism. The hypothalamus produces hormones of its own that directly affect the activity of the pituitary gland.

In some cases, the cause of hypopituitarism is unknown.