Folic Acid Test
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.
- Attach 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 bandage.
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.
- 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.
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
- Ongoing bleeding can be a problem for people with bleeding
disorders. Aspirin, warfarin (such as 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
A folic acid test measures the amount of
folic acid in the blood.
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.
Folate in red blood cells1
317–1422 nmol/L (SI units)
More than 160 ng/mL
More than 362 nmol/L
- High levels of folic acid in the blood may
mean that you eat a diet rich in folic acid, take vitamins, or take folic acid
pills. Consuming more folic acid than the body needs does not cause
- High folic acid levels can also mean a vitamin B12
deficiency. Body cells need vitamin B12 to use folic acid. So if vitamin B12
levels are very low, folic acid can't be used by the cells, and high levels of
it may build up in the blood. But a folic acid test is not a reliable way to
test for a vitamin B12 deficiency.
- Low folic acid levels can mean you have a
problem with your diet,
alcohol dependence, or an eating disorder such as
- Low folic acid levels
can also mean you have a problem absorbing or using folic acid, such as a
vitamin C deficiency, liver disease,
- Low folic acid levels can
cause problems for certain people. For example:
- A pregnant woman needs extra folic acid
for her growing baby.
- People who have
hemolytic anemia, a condition that causes the fast
destruction of red blood cells, need more folic acid to make more
red blood cells.
- People who have certain
conditions, such as kidney failure and some types of cancer, may use up folic
acid quickly. They may need their blood to be cleaned using a machine (kidney dialysis).