Drugs Causing Folate Deficiency (Serum and RBC Effects)
Methotrexate, phenytoin, valproic acid, sulfasalazine, trimethoprim and metformin can skew folate results. See which drugs, by how much, and when to retest.
Folate (Lab Test)
7 source-based articles maintained by the HealthRX.com Editorial Team.
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May 26, 2026latest review
Folate (Lab Test) library
Showing 7 of 7 clinical reviews.
Folate (Serum + RBC): What This Test Actually Measures
A complete clinical guide to the serum folate and RBC folate blood tests: what each compartment measures, normal ranges, causes of high and low results, and how to interpret both values together for MTHFR, methylation, and mood health.
Folate (Serum + RBC): When to Order This Test
Evidence-based guide on when to order serum and RBC folate testing, including clinical indications, interpretation of results, and actionable next steps for patients with suspected folate deficiency or excess.
Folate (Serum + RBC): Which Tests to Order Alongside
A clinical guide to the labs you should pair with serum and RBC folate testing, including vitamin B12, homocysteine, MMA, CBC, and iron studies.
Folate 5.9 ng/mL - What This Result Means
A folate level of 5.9 ng/mL is generally sufficient, above the common 3 ng/mL cutoff. Learn how serum and RBC folate together show true status.
How to Improve Your Folate Levels: Evidence-Based Strategies for Serum and RBC Folate
guide to raising low folate (serum and RBC) through diet, supplementation, and MTHFR-aware strategies. Includes dosing, timelines, and monitoring protocols.
RBC Folate Normal Range vs Optimal Level (140-628 ng/mL)
RBC folate 140-628 ng/mL is normal, but 500+ ng/mL supports methylation and homocysteine control, especially with MTHFR variants. See serum ranges too.