What is prolactin?
- Prolactin is a hormone made in the pituitary gland at the base of the brain
- The only known function of prolactin in humans is stimulation of breast milk production
- Prolactin is also present in men, but there is no known function
Why would prolactin levels be elevated?
There are several causes for high prolactin levels (called hyperprolactinemia), including:
- Prolactin producing tumors in the pituitary gland – these are called prolactinomas
- Use of certain medications including tranquilizers such as Haldol, some antidepressants, Reglan (used for reflux) and some drugs used to treat hypertension
- Pituitary tumors other than prolactinomas or tumors in the area around the pituitary
- Stimulation of the breast, or orgasm shortly before the blood is drawn for the test
Symptoms and problems caused by high prolactin levels in women
- High prolactin will decrease FSH (follicle stimulating hormone) levels. This leads to irregular ovulation and irregular menstrual periods, or no periods at all – amenorrhea.
- Galactorrhea – spontaneous milky nipple discharge (outside of nursing)
- Fertility problems
- A substantial pituitary tumor can cause headaches, and pressure on the optic nerve can cause visual problems
Symptoms and problems caused by elevated prolactin in men
- Low testosterone (male hormone)
- Low sperm count
- Reduced interest in sex, impotence
- Headaches and visual problems, as in women
Treatment for anovulation caused by elevated prolactin levels
There are many causes of anovulation, lack of regular ovulation. Ovulation problems caused by hyperprolactinemia is an uncommon cause of ovulation problems.
High prolactin can cause reduced FSH levels which then results in ovulation problems. The ovulation and fertility problems are treated with drugs to reduce prolactin levels back to normal so that regular ovulation will resume.
Treatment and Success
The first line of treatment for hyperprolactinemia and prolactinomas is medication. In rare cases the tumor is so large that surgery may be first-line treatment. There are two oral medications used to treat high prolactin levels:
With mild to moderate elevations in prolactin, bromocriptine is effective in reducing the level to the normal range in most cases. This usually allows normal, regular ovulation to occur monthly. Women with very high levels of prolactin are less likely to respond well to bromocriptine.
Bromocriptine is better tolerated when started at a low dose and gradually increased over time. Side effects of this medication are related to nausea, dizziness, etc. These side effects decrease over time.
A common way to start Bromocriptine is:
- 1.25 mg taken with a snack at bedtime. This dose is equal to half of a 2.5 mg tablet.
- After 3 days the dose can be increased to 2.5 mg per day (1.25 mg with breakfast and 1.25 mg with a bedtime snack).
- Prolactin levels should be monitored and the drug dose can be increased, if needed
- Eventually, the prolactinoma should decrease in size and prolactin levels should go down to normal.
Bromocriptine can also be taken vaginally, which helps with the nausea problem.
Prolactin levels can be normalized with medications alone (bromocriptine or cabergoline) in about 80% of patients.
Recommended tumor testing for women with high prolactin levels
Women with unexplained elevations of prolactin over about 50-100 (normal prolactin is below about 20-30, depending on the lab) should have CT or MRI scans of the area of the pituitary gland and sella turcica at the base of the brain.
- Usually, MRI scans are done to get the best images – without radiation
- Imaging is done to look for any tumor, and to measure anything that is found
- Future scans can then be done to look for significant tumor growth or shrinkage
- Larger tumors (such as greater than 1 cm. in size) might eventually require surgery if there is not enough response to medication