Prolactin Levels
Reviewed
Also called: PRL test, Prolactin blood test
A prolactin (PRL) test measures the level of prolactin in a sample of your blood.
Specimen: Blood
Why this test may be ordered
- To help diagnose a prolactinoma (a benign pituitary tumor)
- To find the cause of irregular menstrual periods or infertility in women
- To find the cause of infertility, low sex drive, or erectile dysfunction in men
- To monitor a known prolactinoma and check if treatment is working or if the tumor has returned
Preparation and collection
Your provider will let you know if you need to do anything to prepare for your test. You may be asked to fast (not eat or drink) for several hours before your test. For accuracy, your blood sample will usually be scheduled for three to four hours after you wake up. Certain medicines and vitamins can affect prolactin levels. So, be sure to tell your provider about anything you are taking. But never stop taking any medicine without talking with your provider first.
A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.
There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
Understanding results
To understand what the results of your prolactin levels test mean, your provider will consider your symptoms, sex, and medical history, and the results of any other tests you had.
- Higher-than-normal prolactin: In general, for men and women who aren't pregnant or breastfeeding, higher-than-normal prolactin levels may be a sign of many types of conditions, such as: Prolactinoma or another pituitary disorder. Limitation: Higher-than-normal prolactin levels don't always mean you have a medical condition that needs treatment. Diets high in protein and certain medicines can cause high levels. Small increases in prolactin may be caused by stress, exercise, and even having sex. Next step: If your results show high prolactin levels, your provider will usually order other blood tests to help diagnose the cause.
- Lower-than-normal prolactin: Lower-than-normal prolactin levels are rare but may be a sign of a pituitary disorder. Limitation: This is usually the only symptom of abnormally low prolactin levels. Next step: If you have questions about your results, talk with your provider.
- Higher-than-normal levels do not always mean a medical condition needs treatment; small increases can be temporary.
- The test cannot identify the specific cause of abnormal prolactin levels.
- Results must be interpreted alongside symptoms, medical history, and other tests.
What to do next
Treatment for high prolactin levels depends on the cause. If you have questions about your results, talk with your provider.
- What symptoms led to this test being ordered?
- Do I need any additional tests based on my prolactin level?
- Could any medicines or supplements I take affect my prolactin level?
- What does my result mean for my fertility or menstrual cycles?
- How often should I be retested if my levels are abnormal?
Evidence source
Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.