How It Is Done
The health professional drawing blood
- 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
- Put the needle into the vein. More than one needle stick
may be needed.
- Hook a tube to the needle to fill it with
- Remove the band from your arm when enough blood is
- 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
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
There 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
- 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.
- Ongoing bleeding can be a problem for people with
bleeding disorders. Aspirin, warfarin (Coumadin), and other blood-thinning
medicines can make bleeding more likely. If you have bleeding or clotting
problems, or if you take blood-thinning medicine, tell your doctor before your
blood sample is taken.
A prolactin test measures the level of
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.
| Nonpregnant women
4–23 nanograms per milliliter (ng/mL) or 4–23 micrograms per liter (mcg/L)
3–15 ng/mL or 3–15 mcg/L
34–386 ng/mL or 34–386 mcg/L
3.2–20 ng/mL or 3.2–20 mcg/L
- 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
- Other conditions that can cause
high prolactin levels include pregnancy, liver disease (cirrhosis), kidney disease, and
Many conditions can affect prolactin levels. Your doctor will talk with you about any abnormal results in relation to your
symptoms and past health.