Vitamin B-12 and Folate
Does this test have other names?
Cobalamin, Cbl, folic acid, FA
What is this test?
This test measures the levels of vitamin B-12 and folate in your blood.
Your body needs vitamin B-12, also called cobalamin, and folate, also called folic
acid, to function normally. Both nutrients play important roles in creating red blood
cells and making DNA and RNA to help build cells. B-12 also helps your nervous system
function as it should.
B-12 is found in fortified cereals and animal products like fish, meat, eggs, and
dairy. It's also in dietary supplements, as cyanocobalamin. Folate is found naturally
in green leafy vegetables, fruits, and beans. It's also added to enriched cereals
People who have pernicious anemia may have low B-12 levels because this condition
prevents them from absorbing B-12. A low folate level can also be the result of a
poor diet or alcohol abuse.
Why do I need this test?
You may need this test if you are taking medicines that could interfere with how your
body absorbs B-12 or folate. You may also have this test if you have a disease or
condition that could lead to B-12 deficiency. Symptoms of B-12 deficiency include:
Symptoms of having too little folate are diarrhea, weight loss, and other vague symptoms
that could be caused by many other conditions.
It's important that women who are pregnant, thinking of becoming pregnant, or breastfeeding
have enough folate.
This test measures both vitamin B-12 and folate, but either of these nutrients can
be measured separately in different lab tests. Your healthcare provider may order
this combined test if you have a condition for which it's important to know both levels.
What other tests might I have along with this test?
Your healthcare provider may also order these tests:
Homocysteine and methylmalonate, or methylmalonic acid. These substances can build up in your body if you have a B-12 or folate deficiency.
Red blood cell
Pernicious anemia. This includes measuring levels of gastrin, pepsinogen I, pepsinogen II, and antibodies
against a substance called intrinsic factor.
What do my test results mean?
Test results may vary depending on your age, gender, health history, the method used
for the test, and other things. Your test results may not mean you have a problem.
Ask your healthcare provider what your test results mean for you.
Results are given in nanograms per milliliter (ng/mL). A normal range for vitamin
B-12 is 200 to 900 ng/mL.
If your B-12 results are low, it may mean you have:
Your diet can also lead to B-12 deficiency. Some vegetarians or vegans who don't eat
eggs or other dairy products may develop this deficiency.
Your B-12 results may also be higher or lower if you have had recent nuclear medicine
studies using radiation. They can mean that you have:
If the test is done on your blood plasma, a normal range for folate is 2 to 10 ng/mL.
If the test is done on red blood cells, a normal range is 140 to 960 ng/mL.
If your folate results are low, it may mean you have:
How is this test done?
The test is done with a blood sample. A needle is used to draw blood from a vein in
your arm or hand.
Does this test pose any risks?
Having a blood test with a needle carries some risks. These include bleeding, infection,
bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may
feel a slight sting or pain. Afterward, the site may be sore.
What might affect my test results?
Being pregnant can affect your results, as can eating foods that are high or low in
folate. Alcohol use can also affect your results. Certain medicines can also affect
your results. These include:
Birth control pills
How do I get ready for this test?
Tell your healthcare provider about health conditions you have, and how much alcohol
you drink regularly. Be sure your healthcare provider knows about all medicines, herbs,
vitamins, and supplements you are taking. This includes medicines that don't need
a prescription and any illicit drugs you may use.