Hyperprolactinemia (Prolaction Disorder)
What is hyperprolactinemia?
Hyperprolactinemia is the presence of abnormally high levels of prolactin in the blood. Prolactin is a hormone produced in the pituitary gland. Prolactin’s multiple functions in the body mostly involve pregnancy and breast milk production for a newborn baby. However, prolactin can be elevated when a woman is not pregnant or breastfeeding, causing a variety of conditions that can affect normal menstrual function and fertility.
What causes hyperprolactinemia?
Abnormal elevations in prolactin can occur when prolactin-producing cells inside the pituitary, called lactotrophs, produce more of the hormone than required, or when lactotrophs grow abnormally to form tumors. Elevated prolactin levels can also occur as a side effect of certain psychiatric medications.
How is hyperprolactinemia diagnosed?
Simple blood tests to measure the amount of prolactin in the blood can confirm a diagnosis of elevated prolactin levels. Prolactin levels above 25 ng/mL, in women who are not pregnant, are considered elevated. Because each individual experiences daily variations in prolactin levels, it may be necessary to repeat the blood test if levels of the hormone are only slightly elevated. Many women receive this diagnosis after evaluation for infertility or irregular periods, but others have no symptoms at all. Patients will occasionally present with spontaneous milky nipple discharge, but the majority will not experience this symptom. Mild prolactin elevations, between 25-50 ng/mL, do not usually cause noticeable changes in menstrual cycles, though they may decrease overall fertility. Higher prolactin levels between 50-100 ng/mL may cause irregular menstrual periods and significantly decrease a woman’s fertility. Prolactin levels over 100 ng/mL can alter the normal function of a woman’s reproductive system, causing symptoms of menopause (absence of menstrual periods, hot flashes, vaginal dryness) and infertility.
How is hyperprolactinemia treated?
Medications that mimic the brain chemical dopamine can be used successfully to treat the majority of patients with elevated prolactin. These medications limit the production of prolactin from the pituitary and cause prolactin-producing cells to regress. The two most common medications prescribed are cabergoline (Dostinex®) and bromocriptine (Parlodel®). Starting with a small dose that is gradually increased over time can minimize side effects, which include changes in blood pressure and mental “fogginess.” Patients usually respond well to this medication, and prolactin levels will drop in 2 to 3 weeks. Once prolactin levels drop, medication can be adjusted to maintain a normal prolactin level, and can sometimes be discontinued entirely. Spontaneous regression of a tumor will usually occur within a few years without any clinical consequences.
In a small minority of patients, medications are not effective in lowering prolactin levels and large tumors (macroadenomas) persist. These patients are candidates for surgical treatment (transphenoidal adenoma resection) and/or radiation therapy.