Does this test have other names?
What is this test?
This test measures the level of prolactin in your blood. Prolactin is a hormone made
by the pituitary gland, which is in your brain. In women who are pregnant, prolactin
stimulates the breasts to make breastmilk.
If the prolactin-making cells in your pituitary gland begin to grow out of control,
they can form tumors (prolactinomas). Prolactinomas, also known as lactotroph adenomas,
are often not cancer. They happen most often in women younger than 50. One symptom
of a prolactinoma tumor is producing breastmilk even if you're not pregnant. In men,
prolactinomas may cause trouble getting or keeping an erection (impotence) or lower
If you are diagnosed with a prolactinoma, your healthcare provider may give you a
medicine called a dopamine agonist, such as bromocriptine or cabergoline. Cabergoline
works well and has been shown to cut prolactin levels in most people with prolactinomas.
Cabergoline also reduces the size of prolactinoma tumors.
Why do I need this test?
You may need this test if your healthcare provider believes that you have a prolactinoma
tumor. Symptoms of this type of tumor include:
What other tests might I have along with this test?
You may also need an MRI scan of your brain to check for a prolactinoma. You may also
need blood tests to look for other hormones made by the pituitary gland. These include
thyroid-stimulating hormone, luteinizing hormone, and follicle-stimulating hormone.
What do my test results mean?
Test results may vary depending on your age, gender, health history, and other things.
Your test results may be different depending on the lab used. They may not mean you
have a problem. Ask your healthcare provider what your test results mean for you.
Results are given in micrograms per liter (µg/L). A normal blood level of prolactin
in a nonpregnant woman is less than 20 µg/L. In men, the normal level is less than
15µg/L. If your test result shows an abnormally high prolactin level, you may need
imaging tests to find out if you have a prolactinoma tumor.
How is this test done?
The test is done with a blood sample. A needle is used to draw blood from a vein in
your arm or hand.
Does this test pose any risks?
Having a blood test with a needle carries some risks. These include bleeding, infection,
bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may
feel a slight sting or pain. Afterward, the site may be sore.
What might affect my test results?
Certain psychiatric medicines, oral estrogen medicines, cocaine abuse, and opioid
medicines may cause prolactin levels to be higher than normal. If you have kidney
or liver disease, you may also have high prolactin levels.
How do I get ready for this test?
You will need to fast (not eat or drink anything but water) for about 12 hours before
the test. Be sure your healthcare provider knows about all medicines, herbs, vitamins,
and supplements you are taking. This includes medicines that don't need a prescription
and any illegal drugs you may use.