Pregnant women have high levels of prolactin, which helps make breast milk. During pregnancy, prolactin levels increase by 10 to 20 times. After the baby is born, prolactin stays high if you are breast-feeding. In women who do not breast-feed, prolactin levels return to normal soon after they give birth. After months of breast-feeding, prolactin levels may also return to normal levels even if you still breast-feed.
The pituitary glands of men and nonpregnant women also make prolactin but it is not clear what it does in the body for these people.
Prolactin levels are different throughout the day. The highest levels occur during sleep and shortly after you wake up. Prolactin levels also get higher during times of physical or emotional stress.
Many medicines can cause prolactin levels to go up. Tumors of the pituitary gland can sometimes cause prolactin to be made. A damaged pituitary gland may not be able to make normal amounts of prolactin so levels will be lower.
Why It Is Done
A test for prolactin is done:
How To Prepare
Do not eat or drink for a certain number of hours as instructed by your health professional before having a prolactin test.
A blood prolactin test is usually done about 3 hours after you wake up, sometime between 8 a.m. and 10 a.m.
Emotional stress or strenuous exercise just before the test can raise prolactin levels. You may be asked to rest quietly for up to 30 minutes before having your blood drawn.
Stimulation of the nipples can raise prolactin levels. Avoid nipple stimulation for 24 hours prior to prolactin testing. A woman having abnormal nipple discharge should not do anything to cause more discharge before the test.
How It Is Done
The health professional drawing blood will:
How It Feels
The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.
There is very little chance of a problem from having blood sample taken from a vein.
Risks of a blood test
A prolactin test measures the level of the hormone prolactin, which is made by the pituitary gland, in your blood. Prolactin levels are different throughout the day. The highest levels occur during sleep and shortly after you wake up.
The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.
Many conditions can affect prolactin levels. Your health professional will talk with you about any abnormal results in relation to your symptoms and past health.
What Affects the Test
Reasons you may not be able to have the test or why the results may not be helpful include:
What To Think About
eMedicineHealth Medical Reference from Healthwise
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