Folic Acid Test: Procedure, Preparation & Results

Folic Acid Test


Folic acid is the synthetic form of folate or vitamin B9, which is essential for healthy red blood cells. A folic acid test is usually ordered to check for a lack of folate or Vitamin B9. The procedure consists of a simple blood test. Your doctor interprets the results relayed by a lab technician.

Low levels of folic acid may be a sign of anemia, and you may experience symptoms of fatigue. High levels of folic acid are generally not a problem since excess vitamins are normally excreted in urine.

A folic acid test is particularly important for women who are pregnant or intending to get pregnant as a healthy folic acid level protects developing babies against certain birth defects involving the spine, brain, and heart.

What Is Folic Acid?

Folic acid is one of the B-complex vitamins. It is a synthetic version of folate or vitamin B9, which is a naturally occurring vitamin found in vegetables, fruits, meats, and whole grains. The folic acid in supplements is often better absorbed by the body than folate found in food.

Folic acid is necessary for the production of healthy red blood cells, which deliver oxygen to the entire body. It also helps with cell and tissue growth and the creation of DNA, which carries genetic information. Taking 400 micrograms of folic acid during pregnancy can prevent brain and spinal cord birth defects such as spina bifida, according to the National Council on Folic Acid (NCFA). (NCFA)

The Centers for Disease Control and Prevention (CDC) point out that only one-third of women of childbearing age in the United States consume the recommended amount of folic acid from the foods they eat. (CDC, 2012)

Why Have a Folic Acid Test?

B12 or Folate Deficiency

This test may also be used to diagnose B12 or folate deficiency. Signs of a B12 deficiency include:

  • diarrhea or constipation
  • swollen, red tongue
  • bleeding gums
  • lack of appetite


Anemia is a condition caused by a lack of healthy red blood cells. Folic acid is necessary for the production of healthy red blood cells.

Symptoms of anemia include:

  • pallor (skin is unusually pale)
  • fatigue
  • headache
  • sore mouth and tongue

Other Factors

In addition, people with intestinal disorders such as Celiac or Crohn’s disease may have trouble absorbing folic acid and therefore need to be checked regularly. Consuming too much alcohol or following a poor diet might also signal the need for a folic acid test.

Laboratory Blood Test for Folic Acid

Before you take a folic acid test, talk to your doctor about any vitamin supplements or medications you may be taking, as they can interfere with the results. Your doctor will probably tell you to avoid food and liquids for six to eight hours before the folic acid test. It is usually preferable to fast all night and have an early lab appointment the next morning. The test takes place either in the lab area of your physician’s clinic or in a separate facility for laboratory tests.

The lab technician will wrap an elastic band around your upper arm to slow down the flow of blood and cause the veins below the band to swell to make them easier to see. Antiseptic is then applied to the area with a swab prior to the needle poke that draws your blood into a tube. Blood is typically drawn from a vein on the inside of the elbow.

After the blood is collected, the needle is removed, a cotton ball is applied with pressure to stop the tiny amount of bleeding, and the puncture site is covered with a bandage. A lab tech will analyze the folic acid level in your blood and your doctor will interpret the results.

Risks of a Folic Acid Test

The folic acid blood test poses no significant risks. You may get a small bruise where the needle punctured your skin, or rarely, the vein may become swollen. This can be treated with a warm compress.

If you have a bleeding disorder, are on a blood thinner like warfarin (Coumadin), or take aspirin regularly, be sure to tell your doctor before you have a blood test.

What Do the Results of a Folic Acid Test Mean?

The normal reference range of folic acid in the blood is 2.7 to 17.0 nanograms per milliliter (ng/mL). Low levels of folic acid may indicate anemia, malabsorption, or malnutrition.

Folic Acid Recommendations

Get 100 percent of the recommended amount of folic acid daily. Eat a diet rich in folic acid by incorporating these foods into your meals:

  • green, leafy vegetables like spinach, kale, and Swiss chard
  • bok choy
  • broccoli
  • avocados
  • Brussels sprouts
  • beans
  • lentils
  • peas
  • oranges
  • wheat germ
  • whole grains
  • liver
  • fortified cereals

If you are pregnant or are trying to get pregnant, take a daily multivitamin with folic acid.

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