Prolactin is released from the pituitary gland in the brain and has a role in reproduction and lactation. Normal prolactin level should be less than 25ng/ml and can be elevated in 10-15% of women with reproductive disorders. Most common symptoms associated with elevated prolactin levels (hyperprolactinemia) are irregular or absent periods, milky discharge from the breasts, infertility, decreased libido, headaches, visual changes and bone loss (osteopenia or osteoporosis).
Physiological changes that can cause hyperprolactinemia include sleeping, exercise, breast stimulation, food injection, stress, pregnancy and nursing. There are a number of drugs that can elevate prolactin levels and some of these are anti-depressants, anti-psychotics, estrogens, anti-androgens, opiates and medication used to treat high blood pressure. Pathological causes are due to pituitary tumors such as prolactinomas, growth hormone releasing tumors, ACTH secreting tumors, gonadotroph adenomas and non-functional adenomas. Other causes include hypothyroidism, polycystic ovary syndrome (PCOS), chronic renal failure, cirrhosis, chest wall trauma or ectopic secretion such as kidney or ovarian tumors. In some cases, the cause may be unknown or due to the presence of the large prolactin molecule (macroprolactinemia) that can be falsely detected by the prolactin hormone assay.
Once prolactin hormone is found to be elevated, the level should be repeated in the morning without any prior exercise or intercourse/breast stimulation. Once persistently elevated levels are confirmed, physiological and pharmacological causes should be ruled out. Next, imaging of the pituitary gland with magnetic resonance imaging (MRI) should be performed to identify or rule out a pituitary tumor. Pituitary tumors measuring less than 10mm are called microadenomas; those larger than 10mm tumors are named macroadenomas.
Treatment of hyperprolactinemia is mostly medical today, through the use of dopamine agonistic drugs such as bromocriptine or cabergoline. Both drugs are highly effective in normalizing prolactin levels, but cabergoline appears to be a better drug with less side effects. Cabergoline can be stopped after two years of establishing normal prolactin levels with less than 30% recurrence or patients requiring retreatment.
Surgical treatment of tumors causing hyperprolactinemia is reserved for patients who do not respond or cannot tolerate medical therapy, with sudden loss of vision or with multiple complications. The success rate with surgical treatment is higher in smaller sized tumors with a lower rate of recurrence.
Most patients with hyperprolactinemia on medical therapy can stop medications during pregnancy because the risk of tumor enlargement is very low. The ones at highest risk of having symptoms are those with large tumors without any prior treatment. The use of bromocriptine or cabergoline does n