Prolactin levels may be used for several reasons. Prolactin is a hormone produced by the pituitary gland and its primary role is to help initiate and maintain breast milk production in pregnant and nursing women.
Prolactin testing may be used, along with other hormone tests, to help:
Determine the cause of breast milk production not associated with pregnancy or breast-feeding (galactorrhea)
Diagnose the cause of infertility and erectile dysfunction in men
Diagnose the cause of menstrual irregularities and/or infertility in women
Detect and diagnose tumors that produce excess prolactin (prolactinomas), monitor their treatment, and detect recurrences
A person has symptoms of a prolactinoma, such as unexplained headaches, visual impairment, and/or unexplained breast nipple discharge
A woman is experiencing infertility or irregular menstrual periods
A man has symptoms such as decreased sex drive (libido), nipple discharge, or infertility or has a low testosterone level
When a person has a prolactinoma, prolactin levels may be ordered periodically to monitor the progress of the tumor and its response to treatment. They may also be ordered at regular intervals to monitor for prolactinoma recurrence.
Men and non-pregnant women will normally have only small amounts of prolactin in their blood. Prolactin levels do, however, need to be evaluated based on the time of day that they are collected. The levels will vary over a 24-hour period, rising during sleep and peaking in the morning. Ideally, a person's blood sample should be drawn 3 to 4 hours after waking.
A high level of prolactin (hyperprolactinemia) is normal during pregnancy and after childbirth while the mother is nursing.
A high level may also be seen with:
Tumors that produce and release prolactin (prolactinomas)
Stress from illness, chest wall trauma, seizures, lung cancer, and use of marijuana can cause moderate increases in prolactin.
Drugs that can cause an elevated prolactin include estrogen, tricyclic antidepressants, risperidone, opiates, amphetamines, hypertension drugs (reserpine, verapamil, methyldopa) and some drugs that are used to treat gastroesophageal reflux (cimetidine). Nipple stimulation may cause a moderate increase in prolactin blood level.
Low prolactin levels may be caused by drugs such as dopamine, levodopa, and ergot alkaloid derivatives.
Prolactinomas are often small. Along with prolactin levels, a health practitioner may do an MRI (magnetic resonance imaging) of the brain to locate and determine the size of the tumor as well as the size of the pituitary gland.
This article was last reviewed on May 15, 2014. | This article was last modified on December 19, 2014.
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