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Folic acid
Vitamin B9, needed to build red blood cells and DNA — and critical before and during pregnancy.
Other names: Folate, vitamin B9Section: Vitamins
Updated: August 29, 2026·MedProtect editorial team Reference information — not a diagnosis or a prescription
In shortThe normal range is 2.7–17.0 ng/mL (6.12–38.52 nmol/L). The test is often done together with a vitamin B12 test, because a deficiency of either one causes the same megaloblastic anemia.
Reference ranges
Group
Reference range
Adults
2.7–17.0 ng/mL (6.12–38.52 nmol/L)
Normal value ranges vary slightly among different laboratories, and some laboratories use different measurements or test different specimens.
Check your value
Enter the number from your lab report — see how it compares with the typical range. Mind the units shown in the chosen row.
A rough comparison with a typical range, not a diagnosis. Reference ranges vary between laboratories — check the range on your own report and let a clinician interpret the result.
What this marker is
Folic acid is also called vitamin B9. The folate test measures the amount of folic acid in the blood and is often done together with a vitamin B12 test. Folic acid helps form red blood cells and produce DNA, the molecule that stores the body's genetic codes.
The test checks for folic acid deficiency. It is also used in cases of anemia that may be due to folate deficiency, and in megaloblastic anemia — a form of anemia in which red blood cells grow abnormally large because of low folic acid or vitamin B12 levels.
Taking the right amount of folic acid before and during pregnancy helps prevent neural tube defects such as spina bifida. Women who are pregnant or planning to become pregnant should take at least 600 micrograms (mcg) of folic acid every day; it may come from prenatal vitamins and certain foods such as enriched bread, flour, and cereal. Women with a history of neural tube defects in earlier pregnancies may need more — the provider sets the dose.
Results are reported in nanograms per milliliter (ng/mL); in nanomoles per liter (nmol/L) in many countries. The typical normal range is 2.7–17.0 ng/mL (6.12–38.52 nmol/L). Preparation includes fasting — no food or drink for 6 hours before the test — and the provider may pause medicines that interfere, including folic acid supplements themselves.
When it is high
Large amounts are uncommonMedlinePlus notes for B vitamins in general that having large amounts in the body can cause health problems or be due to an underlying health condition such as liver disease; a clearly elevated folate result is read in the context of the full picture, including supplements being taken.
When it is low
Poor dietToo little folate in food is the straightforward cause of a low level.
Malabsorption syndromeConditions such as celiac disease prevent the intestine from absorbing enough folic acid.
MalnutritionA general lack of nutrients lowers folate together with other vitamins.
Megaloblastic anemia linkThe test may be done precisely because anemia is suspected: low folic acid — like low vitamin B12 — produces abnormally large red blood cells.
What can skew the result
These factors can shift the value without any disease — worth considering before a retest:
Food and drink within 6 hours before the testFolic acid supplementsAlcoholMedicines that decrease folic acid measurements: aminosalicylic acid, birth control pills, estrogens, tetracyclines, ampicillin, chloramphenicol, erythromycin, methotrexate, penicillin, aminopterin, phenobarbital, phenytoin, medicines to treat malaria
How to prepare
No food or drink for 6 hours before the test. The provider may pause medicines that interfere with the result — including folic acid supplements; alcohol, aminosalicylic acid, birth control pills, estrogens, tetracyclines, ampicillin, chloramphenicol, erythromycin, methotrexate, penicillin, aminopterin, phenobarbital, phenytoin, and malaria medicines can all decrease folic acid measurements. Nothing is stopped without the provider's advice.
When a retest makes sense
A low result is usually evaluated together with the vitamin B12 level, because the two deficiencies cause the same anemia. Treatment and the retesting schedule are set by the provider; women planning a pregnancy should already be taking at least 600 micrograms (mcg) of folic acid daily.
Who usually reviews this result
A result outside the reference range is usually reviewed by: your GP or primary care doctor; a hematologist if anemia is the concern. Bring your lab report and any previous results to the appointment.
Names used on lab reports
Your report may use any of these names: FolateVitamin B9Folate testFolic acid test
Units and conversion
Measured in: ng/mL
ng/mL=nmol/L
ng/mL × 2.266 = nmol/L. Example: 5.0 ng/mL = 11.3 nmol/L. Results are rounded to 2 decimal places.
Several markers on your report?
See how MedProtect explains results in the app: the whole report, a check of the recognized values, and a clear breakdown.
Because a deficiency of either one causes the same condition — megaloblastic anemia, in which red blood cells grow abnormally large. Measuring both at once separates the two causes.
Why does folic acid matter so much in pregnancy?
Taking the right amount before and during pregnancy helps prevent neural tube defects such as spina bifida. Pregnant women and those planning pregnancy should take at least 600 micrograms (mcg) daily, from prenatal vitamins and enriched foods; after a previous pregnancy affected by a neural tube defect, the provider may set a higher dose.
Which medicines lower the measured level?
Alcohol, aminosalicylic acid, birth control pills, estrogens, tetracyclines, ampicillin, chloramphenicol, erythromycin, methotrexate, penicillin, aminopterin, phenobarbital, phenytoin, and medicines to treat malaria can all decrease folic acid measurements, as can folic acid supplements taken before the test.
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