A pituitary tumor can cause your pituitary gland to produce too much or too few hormones, which can cause problems in your body. Large pituitary tumors — those measuring about 1 centimeter (slightly less than a half-inch) or larger — are known as macroadenomas. Smaller tumors are called microadenomas. Macroadenomas can put pressure on the rest of the pituitary gland and nearby structures.
Symptoms related to tumor pressure
Signs and symptoms of pressure from a pituitary tumor may include:
- Vision loss, particularly loss of peripheral vision
- Nausea and vomiting
- Symptoms of pituitary hormone deficiency
- Less frequent or no menstrual periods
- Body hair loss
- Sexual dysfunction
- Increased frequency and amount of urination
- Unintended weight loss or gain
Symptoms related to hormone level changes
Some pituitary tumors, called functioning tumors, also produce hormones, generally causing an overproduction of hormones. Different types of functioning tumors can develop in your pituitary gland, each causing specific signs and symptoms and sometimes a combination of them.
Adrenocorticotropic hormone-secreting (ACTH) tumors
ACTH tumors produce the hormone adrenocorticotropin, which stimulates your adrenal glands to make the hormone cortisol. Cushing's syndrome results from your adrenal glands producing too much cortisol. Signs and symptoms of Cushing's syndrome may include:
- Fat accumulation around your midsection and upper back
- Exaggerated facial roundness
- A characteristic hump on the upper part of your back
- High blood pressure
- High blood sugar
- Muscle weakness
- Stretch marks
- Thinning of your skin
- Anxiety, irritability or depression
Growth hormone-secreting tumors
These tumors produce excess growth hormone. The effects from excess growth hormone (acromegaly) may include:
- Coarsened facial features
- Enlarged hands and feet
- Excess sweating
- High blood sugar
- Heart problems
- Joint pain
- Misaligned teeth
- Increased growth of body hair
Accelerated and excessive linear growth may occur in children and adolescents.
Overproduction of prolactin from a pituitary tumor (prolactinoma) can cause a decrease in normal levels of sex hormones — estrogen in women and testosterone in men. Excessive prolactin in the blood can affect men and women differently.
In women, prolactinoma may cause:
- Irregular menstrual periods
- Lack of menstrual periods
- Milky discharge from the breasts
In men, a prolactin-producing tumor may cause male hypogonadism. Signs and symptoms may include:
- Erectile dysfunction (ED)
- Loss of sex drive
Thyroid-stimulating hormone-secreting tumors
When a pituitary tumor overproduces thyroid-stimulating hormone, your thyroid gland makes too much of the hormone thyroxine. This is a rare cause of hyperthyroidism or overactive thyroid disease. Hyperthyroidism can accelerate your body's metabolism, causing:
- Sudden weight loss
- Rapid or irregular heartbeat
- Nervousness or irritability
- Frequent bowel movements
- Feeling warm or hot
When to see a doctor
If you develop signs and symptoms that may be associated with a pituitary tumor, see your doctor to determine if this is the cause of your symptoms. Pituitary tumors often can be treated effectively to return your hormone levels to normal and alleviate your signs and symptoms.
If you know that multiple endocrine neoplasia, type I (MEN I) runs in your family, talk to your doctor about periodic tests that may help detect a pituitary tumor early.
The cause of uncontrolled cell growth in the pituitary gland, creating a tumor, remains unknown. The pituitary gland is a small, bean-shaped gland situated at the base of your brain, somewhat behind your nose and between your ears. Despite its small size, the gland influences nearly every part of your body. The hormones it produces help regulate important functions, such as growth, blood pressure and reproduction.
A small percentage of pituitary tumor cases runs in families, but most have no apparent hereditary factor. Still, scientists suspect that genetic alterations play an important role in how pituitary tumors develop.
Although pituitary tumors can occur at any age, they're most likely to occur in older adults. People with a family history of certain hereditary conditions, such as multiple endocrine neoplasia, type I (MEN I), have an increased risk of pituitary tumors. In MEN I, multiple tumors occur in various glands of the endocrine system. Genetic testing is available for this disorder.
Pituitary tumors usually don't grow or spread extensively. However, they can adversely affect your health, possibly causing:
- Vision loss. A pituitary tumor can put pressure on the optic nerves, which are close to your pituitary gland, and cause loss of vision.
- Permanent hormone deficiency. The presence of a pituitary tumor or the removal of one may permanently alter your hormone supply, which may need to be replaced with hormone medications.
- Diabetes insipidus. This is a possible complication of a large pituitary tumor or of some treatments for pituitary tumors. Not to be confused with the more common diabetes mellitus, which involves high sugar levels in the blood and urine, diabetes insipidus is the result of the pituitary making too little vasopressin, which controls the concentration of urine in the kidneys. Diabetes insipidus causes excess amounts of urine and severe thirst, which can lead to dehydration.
A rare but potentially serious complication of a pituitary tumor is pituitary apoplexy, when sudden bleeding into the tumor occurs. Pituitary apoplexy requires emergency treatment, usually with corticosteroids and possibly surgery.