Prolactinoma

Overview

Prolactinoma is a noncancerous tumor of the pituitary gland that produces too much prolactin. The pituitary gland is a small hormone-producing gland located at the base of the brain. Prolactin is a hormone that helps regulate breast milk production and also influences reproductive hormones in both women and men.

Most prolactinomas grow slowly and remain benign. They may be small, called microprolactinomas, or larger, called macroprolactinomas. Even though they are not cancer, larger tumors can press on nearby structures, such as the optic nerves, and cause symptoms related to vision or headaches.

Prolactinoma is one of the more common types of pituitary tumors. With proper medical evaluation, many people can manage the condition effectively and reduce symptoms. Care is usually provided by an endocrinologist, often in collaboration with specialists in neurosurgery, radiology, ophthalmology or reproductive medicine when needed.

Symptoms

Symptoms of prolactinoma are mainly caused by high prolactin levels or by pressure from a larger tumor. Some people have mild symptoms or no symptoms, and the condition may be found during tests for other concerns.

In women, symptoms may include:

• Irregular menstrual periods or absence of periods
• Unexplained milk production from the breasts when not pregnant or breastfeeding
• Difficulty becoming pregnant
• Reduced sexual desire
• Vaginal dryness or discomfort during sexual activity

In men, symptoms may include:

• Reduced sexual desire
• Erectile difficulties
• Infertility or reduced sperm production
• Breast enlargement or tenderness in some cases

Symptoms that may occur in both women and men include headaches, changes in vision, reduced bone strength over time due to low sex hormone levels, and tiredness. Vision problems are more likely when a larger tumor presses on the optic pathways near the pituitary gland.

Causes and Risk Factors

The exact cause of prolactinoma is usually not known. It develops when certain cells in the pituitary gland grow more than expected and produce excess prolactin. Most cases occur without a clear inherited cause.

Possible risk factors and related considerations include:

• Being an adult of reproductive age, although prolactinoma can occur at different ages
• Female sex, especially for smaller tumors that are often detected because of menstrual changes
• Rare inherited endocrine conditions that can increase the chance of pituitary tumors
• Other causes of high prolactin, which must be considered during evaluation, such as pregnancy, thyroid problems, kidney disease, chest wall irritation or certain medications

Not every person with a high prolactin level has a prolactinoma. For this reason, a careful medical assessment is important to identify the cause and plan appropriate care.

Diagnosis

Diagnosis usually begins with a medical history and physical examination. The doctor may ask about menstrual patterns, fertility concerns, sexual function, breast discharge, headaches, vision changes and current medications. In women, pregnancy is typically considered as part of the evaluation when appropriate.

Blood tests are used to measure prolactin levels and may also assess other pituitary hormones, thyroid function, kidney function and reproductive hormone levels. Because prolactin can rise temporarily due to stress, sleep, exercise or other factors, repeat testing may sometimes be needed.

If blood tests suggest prolactinoma, imaging of the pituitary gland is often performed, usually with magnetic resonance imaging. This helps determine the size and location of the tumor and whether it is close to important structures such as the optic nerves.

For larger tumors or when visual symptoms are present, an eye examination and visual field testing may be recommended. These tests check whether the tumor is affecting peripheral vision. Diagnosis is based on the combination of symptoms, hormone test results and imaging findings.

Treatment Options

Treatment depends on the size of the prolactinoma, prolactin level, symptoms, age, fertility goals, general health and whether the tumor is affecting vision or other pituitary functions. The main goals are to lower prolactin levels, reduce tumor size when needed, improve symptoms and protect vision and hormone balance.

Many prolactinomas are treated with medicines that reduce prolactin production and may shrink the tumor. These medicines are prescribed and monitored by a doctor, with follow-up blood tests and sometimes repeat imaging. Treatment response and side effects are reviewed regularly.

Surgery may be considered if medicines are not suitable, not effective enough, not tolerated, or if there is urgent pressure on nearby structures. Surgery is usually performed through a minimally invasive approach via the nasal passages by an experienced pituitary surgeon.

Radiation therapy is used less commonly and may be considered in selected cases when other treatments do not provide adequate control. Some small prolactinomas without significant symptoms may be monitored with regular check-ups rather than treated immediately.

Long-term follow-up is important because prolactin levels, tumor size and pituitary function can change over time. People planning pregnancy or already pregnant should receive individualized specialist guidance, as monitoring and treatment decisions may differ during this period.

When to See a Doctor

Medical evaluation is recommended if you experience unexplained menstrual changes, breast milk production when not breastfeeding, difficulty becoming pregnant, reduced sexual desire, erectile difficulties or persistent headaches. These symptoms can have many causes, and a doctor can help identify the reason.

Seek prompt medical attention if you develop new or worsening vision problems, especially loss of side vision, severe or sudden headache, or symptoms suggesting a major change in pituitary function. These symptoms may require urgent assessment.

If you have been diagnosed with prolactinoma, keep regular follow-up appointments with your endocrinology team. Ongoing monitoring helps ensure that hormone levels, symptoms and tumor size are assessed safely and that treatment is adjusted when necessary.