A clinical biochemistry test that measures the level of folate (folic acid, vitamin B9) in the blood. Used in the evaluation of megaloblastic anemia, pregnancy planning, and nutritional deficiency.
Indication
- Suspected megaloblastic anemia (large-cell anemia)
- Assessment during pregnancy planning and the early stages of pregnancy
- Chronic gastrointestinal disease, malabsorption, celiac disease
- Alcohol use disorder or inadequate nutrition
- Use of medications that affect folate metabolism, such as anticonvulsants (epilepsy drugs) or methotrexate
- Unexplained fatigue, burning tongue, mouth ulcer complaints
Preparation
- An 8-hour fast prior to the test may be requested depending on the laboratory
- If folate-containing supplements or multivitamins were taken in the past 24 hours, this should be disclosed
- The test is sensitive to hemolysis (damage of the blood sample); the sample is drawn carefully
How it's performed
- A venous blood sample is taken from the arm
- The sample is separated into serum or plasma
- Folate level is measured using an immunoassay method
- The result is reported in ng/mL
- When deficiency is suspected, vitamin B12 is evaluated together with folate
Post-procedure
- Results are usually ready within 1-2 business days
- A level below 4 ng/mL is considered low; 4-7 ng/mL is borderline
- If a low level is detected, the physician may recommend dietary changes and supplementation
- For women planning pregnancy, daily 400 mcg folic acid supplementation for at least 1 month before pregnancy and during the first 12 weeks is the standard recommendation in guidelines
- A follow-up test may be recommended 1-3 months after starting treatment
Risks
- Bruising or tenderness at the blood draw site
- Rare fainting; brief pain at the injection site
- If concurrent vitamin B12 deficiency is present, folate supplementation alone may mask neurological findings; therefore, joint evaluation is important
FAQ
Why are folate and B12 tests requested together?
Both vitamins can cause megaloblastic anemia, and giving folate alone in B12 deficiency may mask nerve damage, so it is recommended that the two be evaluated together.
How much folic acid should be taken during pregnancy?
Health authorities recommend 400 mcg of folic acid daily for at least 1 month before pregnancy and during the first 12 weeks. Higher doses may be advised by a physician in higher-risk situations.
Is fasting required?
It varies by laboratory; most centers recommend an 8-hour fast. Confirm the laboratory's instructions before your appointment.
Is eating leafy green vegetables enough?
Diet is important, but during periods of increased need such as pregnancy, diet alone may not be sufficient and supplementation is required.
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