Folate
A B vitamin essential for DNA synthesis, cell division and red blood cell production.
| Typical reference range | above 5.4 ng/mL |
| Commonly cited optimal range | above 10 ng/mL |
Ranges vary by laboratory, method, age and sex: always use the range printed on your own report. Why labs differ.
What it measures
Folate (vitamin B9) occurs naturally in leafy greens, legumes and liver; folic acid is the synthetic form used in fortified foods and supplements. It is needed for making DNA and for methylation reactions, including recycling homocysteine.
Why it matters
Folate deficiency causes macrocytic anemia and elevated homocysteine, and adequate folate before and during early pregnancy prevents neural tube defects.
What a high result can mean
High levels typically reflect supplementation or fortified foods and are not harmful in themselves, but high folic acid intake can mask the anemia of B12 deficiency while nerve damage progresses.
What a low result can mean
Low levels occur with poor diet, alcohol use, malabsorption (celiac disease, IBD), pregnancy, and medications such as methotrexate, trimethoprim, phenytoin and sulfasalazine.
What affects the result
Serum folate reflects recent intake and rises after a single folate-rich meal, so fasting improves accuracy. RBC folate reflects longer-term status. Interpret with B12, homocysteine and MCV.
Units and conversion
Usually reported in ng/mL.
- From nmol/L: multiply by 0.441 to get ng/mL
Also called on lab reports
Folate, Serum, Folic Acid, Serum Folate, Folate (Folic Acid), Serum, Vitamin B9
Related tests: Vitamins & Nutrients
This page is educational and does not replace advice from a healthcare professional.