Prolactinomas

Prolactinomas are benign (non-cancerous) tumors of the pituitary gland that produce an excessive amount of a hormone called prolactin. Located deep inside your brain, the pituitary is a pea- sized gland which plays a significant role in the production of many vital hormones. One of these hormones is prolactin. Prolactin is a hormone that stimulates lactation after childbirth, which is the secretion of milk by the mammary glands of the breast. The symptoms show up due to the increase in the level of prolactin in blood. Prolactinoma can be classified as a microprolactinoma (less than 1cm in diameter) or a macroprolactinoma (more than 1cm in diameter).

Symptoms

Prolactinomas can occur in both men and women, but are more common in women aged 20-50 years. They are rare in children. The symptoms of prolactinomas vary in men and women. Some of these symptoms are due to elevated blood prolactin, while others result from compression of the normal pituitary and surrounding tissues.

In women, an increase in prolactin lowers the level of estrogen. This can lead to infertility, irregular or absent periods, reduced sex drive (libido) and osteoporosis (bone loss). Some women may also develop excess breast milk production known as galactorrhoea.

In men, an increase in prolactin level lowers the testosterone levels and may result in a reduced sex drive (libido) and in impotence. They may also develop breast enlargement, reduced fertility and, very rarely, leakage of milk from the breast.

Symptoms caused by the compression of surrounding tissues

Prolactinomas which are large may press against nearby parts of the pituitary gland and the brain. These may lead to complications such as:

• Headache
• Vision problems: caused by the pressure exerted by the tumor on optic nerves (nerves of the eyes).
• Decrease in production of other pituitary hormones, such as thyroid stimulating hormone and adrenocorticotropic hormone.

What causes Prolactinoma?

The cells in the pituitary gland are responsible for the production of different hormones. Prolactinomas occur when one of these cells in the pituitary gland develops a mutation, which means it multiplies more than usual for no apparent reason and thus leads to the development of a tumor.

Diagnosis of Prolactinoma

Your doctor will perform a physical examination and will ask about the symptoms. They will diagnose prolactinoma based on the results of blood tests and imaging tests.

Blood test

Elevation of prolactin hormone in the body can be checked by a blood test. A very high prolactin level usually indicates that a prolactinoma is present. In some cases, an undiagnosed pregnancy can be mistaken for prolactinoma as prolactin goes up in pregnancy; therefore women will have a pregnancy test first. If the blood test shows that a prolactinoma is likely, an MRI (magnetic resonance imaging) of the brain and pituitary is recommended.

Imaging Test

The preferred test for detecting and measuring prolactinoma is the Magnetic Resonance Imaging (MRI). It creates images of body tissues and allows the doctor to confirm a diagnosis of prolactinoma and determine its size and location. If MRI is not a suitable option for you then your doctor may request a Computed Tomography (CT) scan.

Your doctor might also request an eye test to determine if pituitary tumor has affected your sight.

Treatment of Prolactinoma

The goal of the treatment is to normalize the prolactin level in blood and to decrease the size of the tumor.

Medicines

Medicines called “dopamine agonists” are the first line of treatment for a prolactinoma. They act on the pituitary gland to control the prolactin level and shrink the tumor. Bromocriptine and cabergoline are two most common dopamine agonists used to treat prolactinomas. Bromocriptine must be taken twice or thrice a day. Nausea and dizziness are the two most common side effects associated with bromocriptine. However, they can be minimized by starting with the smallest dose and increasing the dose slowly, if needed. Cabergoline is long acting and is taken once or twice a week. It is more effective than bromocriptine and has fewer side effects.

Surgery

Surgery is recommended if medical treatment is ineffective or if you can’t tolerate the medication. Two types of surgery that may be used are-

• Transsphenoidal surgery: Transsphenoidal surgery, also known as nasal surgery, is the most preferred surgical treatment. This surgery is performed by making an incision at the back of the nasal cavity.
• Transcranial surgery: Transcranial surgery is recommended if the tumor is large or has spread to nearby areas. The surgeon removes the tumor through a small incision in the upper part of the skull.

Radiation

Radiation therapy is considered in people who do not respond to medication and are not good candidates for surgery. Radiation therapy uses high energy rays to destroy the tumor.

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