Causes of Prolactinoma
Prolactinoma is a benign pituitary tumor that overproduces prolactin, which can cause hormonal disturbances such as menstrual irregularities, infertility, and reduced sex drive.
The exact cause of why some people develop prolactinoma is not fully understood, but research suggests that genetic factors may play a role. Some patients may have a hereditary predisposition to developing pituitary tumors, such as in conditions like multiple endocrine neoplasia type 1 (MEN1), where multiple endocrine organs are affected. Hormonal imbalances or changes in the pituitary may also contribute to the development of these tumors.
Although prolactinomas are benign and do not spread, the tumor can grow and cause pressure on surrounding structures, such as the optic nerve.
Symptoms of Prolactinoma
Elevated prolactin levels can disrupt hormonal balance in the body by reducing the release of sex hormones from the pituitary gland. This leads to secondary hypogonadism, which is often one of the first signs of prolactinoma and can cause a variety of symptoms.
- Fatigue and lack of energy: Many people experience constant tiredness despite getting enough sleep.
- Menstrual irregularities: Women may experience irregular periods or absent periods (amenorrhea).
- Milk production: Unusual milk production from the breasts (galactorrhea) can occur even when not pregnant or breastfeeding.
- Reduced sex drive: Both men and women may experience a decrease in libido due to low levels of sex hormones.
- Vision problems: Larger tumors can press on the optic nerve, leading to visual field loss or blurred vision.
Prevalence of Prolactinoma
Prolactinoma is a relatively rare tumor. A Swedish study shows that approximately 1.6 people per 100,000 are affected annually. The condition is most common in women aged 20–40, but after menopause, the prevalence is equal between the sexes. Most affected women have microprolactinomas, where the tumor is smaller than 10 mm. In men, larger tumors, called macroprolactinomas, which are 10 mm or larger, are more common. The average age of diagnosis is around 30 years for women and 40 years for men.
Diagnosis of Prolactinoma
Prolactinoma is usually diagnosed through blood tests that measure the concentration of prolactin, in combination with imaging techniques to confirm the presence of a tumor in the pituitary gland.
- Blood test: A prolactin test measures the amount of prolactin in the blood. Significantly elevated levels can indicate a prolactinoma.
- MRI scan: Magnetic resonance imaging (MRI) is used to visualize the pituitary gland and identify the size and location of the tumor.
- PEG precipitation: A specialized test to differentiate between active prolactin and macroprolactin, which can affect test results.
Prolactin Test in Prolactinoma Investigation
Prolactin tests are used to diagnose and monitor prolactinoma. Elevated prolactin levels often indicate a pituitary tumor. When levels exceed 5000 mIU/L, prolactinoma is suspected, and an MRI scan confirms the diagnosis. Normal reference ranges differ for men and women, with non-pregnant women expected to have prolactin levels between 70 - 350 mIU/L and men between 60 - 260 mIU/L.
Treatment of Prolactinoma
The treatment of prolactinoma focuses on lowering prolactin levels and shrinking the tumor, often with the help of medication:
- Medications: Drugs such as bromocriptine or cabergoline are used to reduce prolactin production and shrink the tumor.
- Surgery: If medications do not work, or if the tumor presses on sensitive parts of the brain, surgery may be necessary to remove it.
- Radiation therapy: In rare cases, radiation therapy may be used if other treatments have not been effective.
- Follow-up: Regular blood tests and MRI scans are performed to ensure the treatment is working and that the tumor does not regrow.