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Folic Acid Test

A folic acid test measures the amount of folic acid in the blood. Folic acid is one of many B vitamins. The body needs folic acid to make red blood cells (RBC), white blood cells (WBC), and platelets, and for normal growth. Folic acid also is important for the normal development of a baby (fetus).

Folic acid can be measured in the liquid portion of blood (plasma). This reflects a person's recent intake of folic acid in the diet. Folic acid is found in foods such as liver; citrus fruits; dark green, leafy vegetables (spinach); whole grains; cereals with added B vitamins; beans; milk; kidney; and yeast.

Folic acid can also be measured as the amount in the red blood cells. This test may be a better way than the plasma test to measure the amount of folic acid stored in the body. The amount of folic acid in red blood cells measures the level when the cell was made, as much as 4 months earlier. This level is not usually affected by the amount of folic acid in your diet each day. It is a more accurate way to measure the body's level of folic acid.

Women who are pregnant or planning to become pregnant need extra folic acid to make more red blood cells and maintain normal growth of their baby. Women who do not get enough folic acid before and during pregnancy are more likely to have a child born with a birth defect, such as a cleft lip or cleft palate or a neural tube defect, such as spina bifida.

Folic acid deficiency can result in a type of anemia called megaloblastic anemia. Mild folic acid deficiency usually does not cause any symptoms. Severe folic acid deficiency may cause a sore tongue, diarrhea, headaches, weakness, forgetfulness, and fatigue.

Why It Is Done

A folic acid test may be done to:

  • Check for anemia. A folic acid test is often done at the same time as a test for vitamin B12 levels because a lack of either vitamin may cause anemia.
  • Check for malnutrition or problems absorbing (malabsorption) folic acid.
  • See if treatment for folic acid deficiency or vitamin B12 deficiency is working.
  • See if a woman has enough folic acid to prevent certain birth defects and allow her baby to grow normally.

How To Prepare

For the folic acid plasma test, do not eat or drink (other than water) for 8 to 10 hours before the test. If you take any medicines regularly, your doctor will talk to you about how to take these before the test.

You do not need to do anything before having a folic acid red blood cell test.

WebMD Medical Reference from Healthwise

Last Updated: December 18, 2012
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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