Folate test

A folate test may be done to:

• Check for the cause of anemia. A folate 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) folate.
• See if treatment for folate deficiency or vitamin B12 deficiency is working.
• See if the folate level is high enough to prevent certain birth defects.

A health professional uses a needle to take a blood sample, usually from the arm.

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.

Normal

Each lab has a different range for what's normal. Your lab report should show the range that your lab uses for each test. The normal range is just a guide. Your doctor will also look at your results based on your age, health, and other factors. A value that isn't in the normal range may still be normal for you.

High values

• High levels of folate in the blood may mean that you eat a lot of foods rich in folate or folic acid, take vitamins, or take folic acid pills.
• High folate levels can also mean a vitamin B12 deficiency. Body cells need vitamin B12 to use folate. So if vitamin B12 levels are very low, folate can't be used by the cells, and high levels of it may build up in the blood. But a folate test is not a reliable way to test for a vitamin B12 deficiency.

Low values

• Low folate levels can also mean that you have a problem absorbing or using folate, such as a vitamin C deficiency, liver disease, celiac disease, sprue, or Crohn's disease.
• Low folate levels can cause problems for certain people. For example:
  • Someone who is pregnant needs extra folate for the growing baby.
  • People who have hemolytic anemia, a condition that causes the fast destruction of red blood cells, need more folate to make more red blood cells.
  • People who have certain conditions, such as kidney failure and some types of cancer, may use up folate quickly. They may need their blood to be cleaned using a machine (kidney dialysis).
• Low folate levels can mean that you aren't getting enough folate in your diet. This is usually only true for people who can't eat very much food, such as people with alcohol use disorder, certain cancers, or an eating disorder.