Pituitary tumors are abnormal growths in the pituitary gland, a small gland at the base of the brain. The pituitary gland is extremely important because it both releases its own hormones and controls hormones released by other endocrine glands, such as the thyroid and adrenal glands, and is thus responsible for regulating multiple systems in the body. For this reason, pituitary tumors can have serious medical consequences.
Pituitary tumors are common, occurring in as much as 20 percent of the population. Most are benign adenomas and many never result in symptoms of any kind. The causes of pituitary tumors are unknown except for those that result from a genetic disorder known as multiple endocrine neoplasia type 1 (MEN1).
Symptoms of Pituitary Tumors
Because pituitary tumors may cause too much or too little hormone secretion, a variety of different symptoms may result. When a tumor of the pituitary damages hormone-producing cells of the gland, the result will be hypopituitarism. When a tumor results in excessive hormone secretion, any of the following symptoms may occur:
- Hyperthyroidism (overactive thyroid gland)
- Cushing's syndrome (over production of ACTH or steroid production)
- Acromegaly or gigantism (over production of grown hormone)
- Nipple discharge (from prolactin over production)
Pituitary adenomas are categorized by size as either macroadenomas or microadenomas. Macroadenomas cause pressure which may result in the following symptoms:
- Nausea or vomiting
- Nasal drainage
- Difficulties with sense of smell
- Double vision, diminished visual field, drooping eyelids
Although rare, in some cases, these symptoms of pressure may appear suddenly and be severe.
Diagnosis of Pituitary Tumors
In order to diagnose a pituitary tumor, a comprehensive physical examination and several diagnostic tests are necessary, including an MRI scan of the head and tests to assess the patient's field of vision. Hormone levels, which may be measured in the blood or urine, must also be tested. These include levels of cortisol, insulin, prolactin, testosterone, estradiol, and thyroid hormones.
Treatment of Pituitary Tumors
Since most pituitary tumors are not malignant, there is usually no danger of metastasis. Nonetheless, as a pituitary tumor grows, the pressure on significant blood vessels and nerves can cause serious, and sometimes dangerous, complications. Treatment of a pituitary tumor most often involves surgical excision, especially if the tumor is pressing on the optic nerve.
Most pituitary tumors can be removed through the nose and sinuses, but some require transcranial surgery. For patients who are not candidates for surgery, radiation therapy may be used to shrink the tumor. Radiation therapy may also be used in conjunction with surgery to make sure the entire tumor has been removed. For certain types of pituitary tumors, medications are also administered.
Risks of Pituitary Tumors
The risks of untreated pituitary tumors and the risks of their surgical removal are similar. Because of the gland's proximity to the optic nerve, there is a danger or blindness as a result of pressure on the nerve by the tumor or damage to the nerve during surgery. Because the pituitary gland releases and controls so many hormones, unaddressed tumor growth or surgery may cause permanent hormone imbalance. Hormone replacements may have to be taken and monitored for the remainder of the patient's life.