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 change (mutate) and
grow out of control, they can form tumors (prolactinomas). Prolactinomas, also known
as lactotroph adenomas, are usually not cancerous. They happen most often in women
younger than 50. One symptom of a prolactinoma tumor is breastmilk even if you're
not pregnant. In men, prolactinomas may cause impotence or lower sex drive.
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
seems to work best. It has been shown to cut prolactin levels in roughly 90% of people
with prolactinomas. Cabergoline also reduces the size of prolactinoma tumors.
Why do I need this test?
You may have this test if your healthcare provider suspects that you have a prolactinoma
tumor. Symptoms of this type of tumor include:
What other tests might I have along with this test?
Your healthcare provider may also order 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
What do my test results mean?
Many things may affect your lab test results. These include the method each lab uses
to do the test. Even if your test results are different from the normal value, you
may not have a problem. To learn what the results mean for you, talk with your healthcare
Results are given in micrograms per liter (µg/L). A normal blood level of prolactin
is less than 20 µg/L. If your test result shows an abnormally high prolactin level,
you may need imaging tests to find out whether you have a prolactinoma tumor.
How is this test done?
The test requires a blood sample, which is drawn through a needle from a vein in your
Does this test pose any risks?
Taking a blood sample with a needle carries risks that include bleeding, infection,
bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight
stinging sensation or pain. Afterward, the site may be slightly sore.
What might affect my test results?
Certain psychiatric medicines, oral estrogen drugs, and hypothyroid 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 don't need to prepare for this test.