What are the signs of pituitary adenomas?

There are two general types of pituitary adenomas. Adenomas that grow in size are called macroadenomas . These can exert pressure on nearby structures due to their increased size. Most commonly, because the pituitary gland sits right underneath the optic chiasm, macroadenomas can affect vision. This usually presents as loss of peripheral vision on both sides, but can also present as other patterns of vision loss. The pressure of pituitary macroadenomas can also lead to headaches, and invasion into nearby nerves can cause other neurologic signs, such as loss of motion of the eye.

Adenomas that remain small are called microadenomas . If these cause symptoms, it is because they produce excessive amounts of hormones, although macroadenomas can also secrete and produce hormones. Depending on which hormones they secrete, the signs and symptoms of these adenomas can differ. For example, prolactin-secreting adenomas can result in milk production from the breast, while growth hormone-producing adenomas can cause acromegaly.
Some adenomas do not produce any symptoms at all. Most of these are found incidentally during the workup of another unrelated problem. Many people may have pituitary adenomas and never know it because they do not have symptoms. In fact, some reports state that up to 25% of people undergoing autopsy after death have been found to have pituitary adenomas that they never knew about because the tumor did not cause any symptoms.

What causes pituitary adenomas and am I at risk?

Each year, there are approximately 2,000 cases of pituitary tumors in the United States . The cause of most pituitary tumors is unknown, although there may be a genetic factor. For example, there is a mutation in a specific gene that is associated with increased risk for developing pituitary adenomas. Pituitary tumors develop in 30% percent of patients with multiple endocrine neoplasia type 1 (MEN-1). Mutations in the MEN-1 gene are rarely found in sporadic cases (which means cases that do not run in families) of pituitary tumors, but are almost always found in every case of familial pituitary tumors. Patients with MEN-1 are also at increased risk for developing parathyroid and pancreas tumors.

Another gene called gsp may be involved in sporadic cases of pituitary tumor. Mutations in the gsp gene have been found in 10% of non-secreting pituitary adenomas, 40% of pituitary adenomas secreting growth hormone, and 5% of pituitary adenomas secreting ACTH.
Aside from these genetic mutations, no other cause is known for pituitary tumors. Pituitary tumors are not associated with smoking or drinking and have not been linked with any viral infections. The risk of pituitary adenomas does increase with age, and they are slightly more likely to occur in women than men, although the exact reason for this is unknown.