RBC Folate

"Folate RBC" means red blood cell folate — a lab measure of folate inside erythrocytes. It reflects long-term folate status over the roughly 120-day lifespan of red blood cells and is less influenced by recent meals than serum folate. Clinicians use it to detect chronic folate deficiency and to monitor folate supplementation, particularly during pregnancy or when investigating anemia.

High red‑blood‑cell (RBC) folate usually reflects recent high intake — folic acid supplements or fortified foods — or physiologic states like pregnancy. It can also be raised after blood transfusion, with liver disease, or from lab/measurement variation. Very high folate can mask vitamin B12 deficiency, so discuss results with your clinician to review supplements, diet, medications and consider checking B12 and liver tests.

Very high folate—usually from supplements or fortified foods—can mask vitamin B12 deficiency, delaying diagnosis and risking irreversible nerve damage. Excess folic acid has been linked in some studies to faster growth of existing cancers and possible increased cancer risk. Other effects may include sleep changes, irritability, or gastrointestinal symptoms. Discuss abnormal results and supplement use with your clinician.

Low red blood cell (RBC) folate commonly stems from inadequate dietary intake or chronic alcohol use, malabsorption (celiac disease, inflammatory bowel disease, post‑bariatric surgery), and increased requirements (pregnancy, hemolysis, rapid growth). Certain medications (methotrexate, anticonvulsants, sulfasalazine, trimethoprim) and chronic illnesses (liver disease, dialysis, malignancy) can also deplete folate stores or poor supplementation.

Low folate typically causes megaloblastic anemia symptoms: fatigue, weakness, pallor, shortness of breath, rapid heartbeat and lightheadedness. It may also cause irritability, headaches, poor appetite, weight loss, diarrhea, and a sore or inflamed tongue with mouth ulcers. Neurological signs—numbness, tingling, memory or concentration problems—can occur, and in pregnancy it raises neural tube defect risk.

A good RBC folate level is generally considered ≥906 nmol/L (about 400 ng/mL) — the concentration linked with a low risk of neural tube defects in pregnancy. Values substantially below this, often under roughly 305–340 nmol/L (≈135–150 ng/mL), suggest deficiency. Reference ranges vary by lab, so review your report and discuss supplementation or treatment with your healthcare provider.