A prolactin test measures the level of the
hormone prolactin, which is made by the
pituitary gland , in your blood.
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.
pituitary glands of men and nonpregnant women also make prolactin but it is not
clear what it does in the body for these people.
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:
- To find the cause of abnormal nipple discharge,
or if a woman is not having periods (amenorrhea) or if a woman is having a hard
time becoming pregnant (infertile).
- In a man when a
pituitary gland problem is suspected. Also, a prolactin test may be done to
check levels if a man lacks sexual desire or if he has trouble getting an
erection (erectile dysfunction). Prolactin levels may be checked
when a man's testosterone levels are really low.
- To see whether a
tumor in the pituitary gland (called a prolactinoma) is making large amounts of
How To Prepare
Do not eat or drink for a certain
number of hours as instructed by your doctor before having a
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.