A pituitary adenoma is a tumor in the pituitary gland, located at the base of the brain.
Pituitary adenomas are typically benign tumors, which means they do not spread beyond the pituitary gland. About 1 in 1100 people have a pituitary adenoma that is detected either because of symptoms or by testing for an unrelated condition.
Different Types of Pituitary Adenomas and Their Symptoms
Approximately half of patients diagnosed with pituitary adenomas have microadenomas (<10 mm in size) and half have macroadenomas (≥10 mm). Pituitary adenomas are classified as functioning (70%) or nonfunctioning (30%).
Functioning pituitary adenomas produce excess hormones that can lead to health problems. About half of functioning pituitary adenomas produce excess prolactin (a hormone that normally stimulates milk production after giving birth). These tumors can cause lack of menstruation, female infertility, vaginal dryness, low male libido, low male testosterone levels, and erectile dysfunction. Pituitary adenomas with increased production of growth hormone can cause enlargement of hand, foot, and facial features; headache; osteoarthritis; diabetes; sleep apnea; and high blood pressure. Pituitary adenomas that secrete corticotropin (a hormone that releases cortisol from the adrenal gland) can cause obesity, high blood pressure, osteoporosis, anxiety, depression, and sleep problems. Pituitary adenomas with excess secretion of thyrotropin can result in hyperthyroidism, which may cause sweating, rapid or irregular heartbeat, irritability, and unexpected weight loss.
Nonfunctioning pituitary adenomas do not produce hormones but can cause headaches or partial loss of vision by compressing the optic nerves and can interfere with normal pituitary function.
How Are Pituitary Adenomas Diagnosed?
Patients with a known or suspected pituitary tumor should undergo high-resolution magnetic resonance imaging (MRI) of the brain to assess the adenoma size and location. Blood tests for specific hormone levels should be performed to determine whether it is a functioning or nonfunctioning pituitary adenoma.
How Are Pituitary Adenomas Treated?
First-line treatment for most pituitary adenomas (except those with high prolactin levels) is surgery, which is most commonly performed using a minimally invasive technique called transsphenoidal pituitary surgery. During this procedure, instruments are passed through the nasal passages to remove the tumor. Much less commonly, pituitary adenomas that are very large may be treated with more invasive surgery (craniotomy), which involves the temporary removal of bone from the skull to access the tumor. After surgery, approximately 5% to 15% of patients develop recurrent pituitary adenomas. Patients who have persistent or recurrent pituitary adenoma after surgery may be treated with medications or radiation therapy.
First-line therapy for a prolactin-secreting pituitary adenoma is medication. The 2 drugs approved by the US Food and Drug Administration (FDA) for treating these types of pituitary adenomas are bromocriptine and cabergoline.
Nonfunctioning microadenomas that are not causing any symptoms may not need to be treated but should be monitored with MRI scans at regular intervals.
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Published Online: November 10, 2023. doi:10.1001/jama.2023.15248
Conflict of Interest Disclosures: None reported.
Source: Tritos NA, Miller KK. Diagnosis and management of pituitary adenomas: a review. JAMA. 2023;329(16):1386-1398. doi:10.1001/jama.2023.5444