Folate (Folic Acid)
Also known as: Folic acid, Vitamin B9, Red cell folate
Folate is essential for DNA synthesis and cell division — it is critically important in early pregnancy for preventing neural tube defects, and together with B12 it prevents megaloblastic anaemia.
Venous blood (serum separator tube); Red cell folate requires EDTA
24–48 hours
Required
Vitamins & Minerals
Folate rises transiently after eating — fast for 8 hours for serum folate. Red cell folate is unaffected by fasting.
Reference Ranges
| Measurement | Reference Range | Unit |
|---|---|---|
| Serum folate (normal) | ≥ 4 | ng/mL |
| Serum folate (deficiency) | ≤ 4 | ng/mL |
| Red cell folate (normal) | ≥ 140 | ng/mL |
Reference ranges are typical adult values. Your laboratory may use slightly different intervals — always use your lab's reported reference.
What This Test Measures
Folate is a B-vitamin that drives one-carbon metabolism — the biochemical pathway that produces DNA building blocks and methylates genes. Serum folate reflects recent dietary intake and fluctuates day to day. Red cell folate, stored inside red blood cells for 90 days, reflects long-term folate status, like HbA1c for glucose. Both markers together give the full picture.
When Is This Test Ordered?
- Investigating macrocytic anaemia (always pair with B12)
- Pre-conception counselling and early pregnancy monitoring
- Patients on methotrexate or anti-epileptics that impair folate metabolism
- Malabsorption syndromes
- Neural tube defect risk reduction
When Results Are High
High folate from supplementation is generally safe — folate is water-soluble with a wide therapeutic window. Very high folate can mask B12 deficiency by correcting megaloblastic anaemia while neurological damage continues — always test B12 alongside folate.
When Results Are Low
Low folate causes megaloblastic anaemia (large, dysfunctional red blood cells) indistinguishable from B12 deficiency on blood smear. In pregnancy, deficiency before week 4 (before many women know they are pregnant) causes neural tube defects (spina bifida, anencephaly). Supplements must be started pre-conception.
Factors That Can Affect Your Result
- Recent dietary folate (leafy greens, legumes, fortified cereals) raises serum levels transiently
- Alcohol impairs folate absorption and raises excretion
- Methotrexate is a folate antagonist — patients must supplement
- Anti-epileptics (phenytoin, valproate) reduce folate absorption
- Haemolysis falsely raises serum folate (folate released from ruptured RBCs)
Tracking This Test Over Time
Women planning pregnancy should take 400–800 mcg of folic acid at least 1 month before conception and throughout the first trimester. Women with a prior neural tube defect pregnancy require 4 mg/day (10× the standard dose) — ensure the dose is correct on your first prenatal visit.
Track your Folate in LoomsRelated Tests
B12
Vitamin B12 is essential for nerve function, DNA synthesis, and red blood cell production. Deficiency develops slowly — often over years — and can cause irreversible neurological damage before blood cell changes appear.
CBC
A CBC measures all three types of blood cells — red cells, white cells, and platelets — along with haemoglobin and haematocrit. It is one of the most ordered tests in medicine because it screens for dozens of conditions in a single draw.
Medical disclaimer
This page is for educational purposes only and does not constitute medical advice. Reference ranges vary between laboratories, and results must be interpreted in the context of your symptoms, history, and other tests. Always discuss your results with your healthcare provider. Content reviewed by the Looms medical team, 2026-06-01.