Vitamin B12 Test
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
- 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 vitamin B12 test measures the amount of
vitamin B12 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.
- High levels of vitamin B12 can occur in liver
disease (such as
hepatitis) and some types of
leukemia. But the vitamin B12 test is not usually used
to diagnose these problems.
- In rare cases, high levels may be found
in people with
diabetes or who are
- Low levels of vitamin B12 may mean you have vitamin B12 deficiency anemia, which might be caused by problems
with the absorption of the vitamin (such as pernicious anemia).
- Low levels
may also occur following removal of part or all of the stomach (gastrectomy),
gastric bypass surgery, or gastric stapling surgery, or following surgery to
remove part of the small intestine where this vitamin is absorbed (terminal
- Low levels may mean an infection with a
parasite called fish tapeworm is
- In rare cases, low levels may mean a person is not getting
enough vitamin B12 in his or her food.
- Low levels are linked with
folic acid deficiency anemia.
- High levels of protein in
the blood, such as from
multiple myeloma, can falsely decrease blood vitamin