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Folic acid - test

Folic acid is a type of B vitamin. This article discusses the test to measure the amount of folic acid in the blood.


Alternative Names

Folate - test

How the test is performed

Most of the time blood is taken from a vein, on the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.

Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.

Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.

How to prepare for the test

You should not eat or drink for 6 hours before the test. Your health care provider may tell you to stop taking any drugs that may interfere with test results, including folic acid supplements.

Drugs that can decrease folic acid measurements include alcohol, aminosalicylic acid, birth control pills, estrogens, tetracyclines, ampicillin, chloramphenicol, erythromycin, methotrexate, penicillin, aminopterin, phenobarbital, phenytoin, and drugs to treat malaria.

How the test will feel

You may feel slight pain or a little sting when the needle is inserted. There maybe some throbbing at the site.

Why the test is performed

This test is done to check for folic acid deficiency .

Folic acid helps form red blood cells and produce DNA that stores genetic codes. Taking the right amount of folic acid before and during pregnancy helps prevent certain birth defects, such as spina bifida.

Women who are pregnant or planning to become pregnant should take at least 400 micrograms (mcg) of folic acid every day. Pregnant women need even higher levels of folic acid. Ask your health care provider how much you need.

Normal Values

The normal range is 2.7 - 17.0 nanograms per milliliter (ng/mL).

Note: Normal value ranges may vary slightly among different labs. Talk to your doctor about the meaning of your specific test results.

The examples above show the common measurements for results for these tests. Some labs use different measurements or may test different specimens.

What abnormal results mean

Lower-than-normal folic acid levels may indicate:

The test may also be done in cases of:

What the risks are

There is very little risk involved with having your blood taken. Veins and arteries vary in size. It may be harderto take a blood sample in one person than another.

Other slight risks from having blood drawn may include:

  • Excessive bleeding
  • Fainting or feeling light-headed
  • Hematoma (blood accumulating under the skin)
  • Infection (a slight risk any time the skin is broken)

References

Elghetany MT, Banki K. Erthrocytic Disorders. In: Mcpherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 32.

Antony AC. Megaloblastic Anemias. In: Hoffman R, Benz EJ Jr, Silberstein LE, Heslop HE, Weitz JI, eds. Hematology: Basic Principles and Practice. 6th ed. Philadelphia, Pa: Saunders Elsevier; 2012:chap 32.

Mason JB. Vitamins, trace minerals, and other micronutrients. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 225

Updated: 2/18/2013

Alison Evert, MS, RD, CDE, Nutritionist, University of Washington Medical Center Diabetes Care Center, Seattle, Washington. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, Bethanne Black, Stephanie Slon, and Nissi Wang.


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