Prolactin
Test OverviewA 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 breastfeeding.
In women who do not breastfeed, prolactin levels return to normal soon after
they give birth. After months of breastfeeding, prolactin levels may also
return to normal levels even if you still breastfeed. 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 DoneA 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
prolactin.
How To PrepareDo not eat or drink for a certain
number of hours as instructed by your doctor 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 DoneThe health professional drawing blood
will: - Wrap an elastic band around your upper arm to
stop the flow of blood. This makes the veins below the band larger so it is
easier to put a needle into the vein.
- Clean the needle site with
alcohol.
- Put the needle into the vein. More than one needle stick
may be needed.
- Hook a tube to the needle to fill it with
blood.
- Remove the band from your arm when enough blood is
collected.
- Put a gauze pad or cotton ball over the needle site as
the needle is removed.
- Put pressure on the site and then put on a
bandage.
How It FeelsThe 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. RisksThere is very little chance of a problem from
having a blood sample taken from a vein. Risks of a blood test- You may get a small bruise at the site. You
can lower the chance of bruising by keeping pressure on the site for several
minutes.
- In rare cases, the vein may become swollen after the blood
sample is taken. This problem is called phlebitis. A warm compress can be used
several times a day to treat this.
ResultsA 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. NormalThe 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. Prolactinfootnote 1| Nonpregnant women | 4-23 nanograms per milliliter (ng/mL) or 4-23 micrograms per liter (mcg/L) |
|---|
| Men | 3-15 ng/mL or 3-15 mcg/L |
|---|
| Pregnant women | 34-386 ng/mL or 34-386 mcg/L |
|---|
| Children | 3.2-20 ng/mL or 3.2-20 mcg/L |
|---|
High values- High levels of prolactin (usually higher than 200
ng/mL) may mean a pituitary gland tumor (prolactinoma) is present. The higher
the prolactin level, the more likely a pituitary gland tumor is present. If a
prolactin level is over 200 ng/mL, a
magnetic resonance imaging (MRI) test may be done to
confirm a pituitary tumor is present. A normal or low prolactin level does not
always mean there is no pituitary tumor. An MRI test may be done if a pituitary
tumor is suspected.
- High levels of prolactin may
mean that the pituitary gland is making excess prolactin for unknown reasons
(idiopathic hyperprolactinemia).
- Other conditions that can cause
high prolactin levels include pregnancy, liver disease (cirrhosis), kidney disease, and
hypothyroidism.
Many conditions can affect prolactin levels. Your doctor will talk with you about any abnormal results in relation to your
symptoms and past health. What Affects the TestReasons you may not be able to
have the test or why the results may not be helpful include: - Having a lot of emotional stress or doing
strenuous exercise before the test.
- Trouble sleeping. Prolactin
levels are highest during sleep. So if you do not sleep well, your levels may be
lower than normal.
- Stimulating your nipples.
- Taking
certain medicines, such as birth control pills, high blood pressure medicines,
tricyclic antidepressants, or medicines for mental illness, such as
phenothiazines.
- Using cocaine.
- Having a test with
radioactive tracer a week before the prolactin test.
What To Think About- Men and nonpregnant women normally have low
levels of prolactin. The only known problem caused by a lack of prolactin is
not being able to make milk after pregnancy. So even people who have an
abnormally low level of prolactin are not treated for the
condition.
- Men may have a prolactin test 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 learn more, see the topic
Testosterone.
- Treatment for a pituitary gland tumor that is making too
much prolactin includes medicines (such as bromocriptine), removing the
pituitary gland, or radiation therapy to the gland. The choice of treatment is
based on the size of the tumor and the health and age of the person being
treated.
ReferencesCitations- Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
Other Works Consulted- Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
- Pagana KD, Pagana TJ (2010). Mosby's Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.
CreditsByHealthwise Staff
Primary Medical ReviewerSarah Marshall, MD - Family Medicine
E. Gregory Thompson, MD - Internal Medicine
Kathleen Romito, MD - Family Medicine
Specialist Medical ReviewerDeborah A. Penava, BA, MD, FRCSC, MPH - Obstetrics and Gynecology Current as of:
May 3, 2017 Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins. Last modified on: 8 September 2017
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