Does this test have other names?
Vitamin B-9, folic acid test
What is this test?
This is a blood test to measure the concentration of folate in the liquid part of
your blood, called serum, or in your red blood cells. The concentration in the red
blood cells will be higher than in the serum.
Folate is the natural form of vitamin B-9 found in:
Leafy green vegetables, such as spinach, kale, collards, and romaine lettuce
Citrus fruits and juices
Dried beans, lentils, and peas
Many cereals, breads, and other grain products are fortified with folic acid, the
synthetic version of vitamin B-9.
Folate is needed to make red blood cells. It is also used to repair cells and to make
It also helps prevent cellular changes that may lead to cancer. Folate is also needed
to help a baby's cells multiply during pregnancy. Low levels of folate during pregnancy
can lead to brain or spine defects in the fetus. It can also lead to megaloblastic
anemia. This is a type of anemia marked by fewer, but larger, red blood cells.
Why do I need this test?
You may need this test to find out the cause of anemia, look at your nutritional status,
or keep track of a previous folate deficiency.
If you have anemia, you don't have enough red blood cells to carry oxygen to the cells
in your body. A folate deficiency is just 1 cause of anemia. If you don't get enough
folate or folic acid from food or vitamins, you may end up with a folate deficiency.
Pale skin, gums, eyes, and nails
Mouth ulcers and a red, sore tongue
Shortness of breath
Numbness and tingling of fingers and toes
Fluttering heartbeat (palpitations) or rapid heartbeat
Dizziness and fainting
Nausea, vomiting, diarrhea, although these are rare
What other tests might I have along with this test?
Your healthcare provider may also order a vitamin B-12 test. Both folate and B-12
are important for healthy red blood cells. A deficiency in either B-12 or folate can
What do my test results mean?
Test results may vary depending on your age, gender, health history, and other things.
Your test results may be different depending on the lab used. They may not mean you
have a problem. Ask your healthcare provider what your test results mean for you.
For blood plasma or serum, a normal result ranges from 2.5 to 20 nanograms per milliliter
(ng/mL) or 4.5 to 45.3 nanomoles per liter (nmol/L).
For red blood cells, a normal result ranges from 140 to 628 ng/mL or 317 to 1,422
A test result that's lower than normal means you have a folate deficiency, and your
healthcare provider may recommend folic acid supplements. Once you begin taking supplements,
the folate deficiency will go away within a few months. Your healthcare provider determines
how much of a folic acid supplement you need based on your age and whether you are
pregnant or breastfeeding.
Folate is water soluble, so any extra folate leaves your body in urine. But a buildup
can sometimes happen during folic acid therapy.
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?
Many factors can contribute to a folate deficiency, including:
Being a vegetarian or not eating enough fresh vegetables and fortified grains
Drinking too much alcohol
Birth control pills
Nutrition absorption problems (such as Crohn disease or celiac disease)
How do I get ready for this test?
You don't need to prepare for this test. 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 illegal drugs you may use.