A tumor in the pituitary gland causes symptoms by either releasing too much of a hormone or by pressing on the gland causing it to release too little hormone. The symptoms one experiences from the pituitary tumor are determined by the type of tumor. A pituitary tumor may also cause symptoms by growing and pressing on the structures surrounding the pituitary gland, like the nerves to the eyes.

A pituitary tumor can cause an increase in any of the anterior pituitary hormones listed in Table 3.1. For example, you may experience the following:

In a condition called acromegaly [1, 2], an increase in the amount of growth hormone (GH), causes the body to grow at an abnormally fast rate. Bones become thicker and the hands and feet may appear wider or bigger, and the jaw may protrude. Carpal tunnel syndrome and spinal problems may develop due to excessive growth of bone and soft tissue. Many patients develop diabetes, high blood pressure, and cardiac problems. This tumor shortens life span.

In Cushing’s disease [2, 3], a tumor releases adrenocorticotropic hormone (ACTH) which produces an increase in the body’s own steroid called cortisol, which leads to fat deposits, especially in the shoulders and face, and increased growth of body hair. Brittle diabetes and severe high blood pressure that can be difficult to control, even with many medications, is common. Patients often develop softening of the bones, called osteoporosis. Left untreated, this is a life threatening problem.

With a tumor making too much prolactin called a prolactinoma [2, 4, 5], elevated levels of prolactin may cause secretion of breast fluids and decreased sexual drive and breast enlargement in men and women. It may also cause irregular or absent menstrual periods in women, and difficulty in having an erection or infertility in men. Many women note weight gain and mood swings. Men may have a decrease in testosterone levels because of this tumor.

For pituitary tumors that do not secrete hormones [2], the initial symptoms may not occur until the tumor presses on the structures surrounding the normal pituitary gland. This is why such tumors are often quite large when they are discovered.

Because the pituitary gland is located near the eyes, it can press on the nerves to the eyes and cause loss of vision. Loss of peripheral vision (See Fig. 3.2) may occur first and be undetected. This may progress to eventual blindness if the pressure is not removed from the nerves. Almost any kind of visual problem can be seen with large pituitary tumors. The tumor may also press on the nerves that move the eye and cause double vision. If the tumor is very large it may press on other parts of the brain and cause problems with memory, weakness, numbness, or increased pressure in the brain because of impaired circulation of the brain fluid.

Most pituitary tumors can be cured or at least very well controlled with the treatments that are available. Treatment options include observation over a period of time to see if treatment is needed, treatment with drugs, radiation therapy, and surgery

Since most pituitary tumors are usually benign, some tumors may be observed without treatment because they may grow very slowly. If a decision is made to observe the tumor, ongoing evaluations with CT or MRI scans, and assessment by an endocrinologist and possibly an ophthalmologist will be performed. CT or MRI scans will be performed within 3–6 months after the initial diagnosis and every 6–12 months thereafter until the situation has been clarified. This period of observation without treatment provides information that helps the doctors decide whether other treatments that have more risks are needed.

Observation without treatment may also be recommended if conditions are present that would seriously increase the risk of surgical or other treatments. Because pituitary tumors are slow growing, patients can often be observed without treatment for long periods of time without the tumor causing serious problems. This can be the recommended form of treatment for patients who are age 70 or above or who have a serious medical illness such as heart disease. Close follow-up will be necessary to monitor tumor growth and symptoms.

Only one type of pituitary tumor can be successfully treated with drugs. This type of tumor, called a prolactinoma, secretes a hormone called prolactin.

Prolactinomas can often by controlled by a drug called Bromocriptine, or another newer drug called Cabergoline [5]. These drugs will often reduce the size of the tumor and at the same time produce a decrease in the abnormally high prolactin level in the blood. Although the drugs may control the tumor, they will not cure it. Treatment in most cases must be continued for many years. While these drugs are effective in many cases, some patients develop nausea, headache, dizziness, and weakness while taking them. Usually these symptoms can be reduced by taking small doses of the drug at first and slowly increasing the dosage up to the needed level over a period of several weeks or months. These drugs will not control all prolactin-secreting tumors. For approximately 20 % of patients with prolactinomas, surgery or radiation therapy may be needed.