Folate, RBC
What This Test Measures
Red blood cell folate; reflects longer-term folate status (2-3 months) versus serum folate (days).
Preparation
PREP: No fasting required for RBC folate (unlike serum folate). RBC folate is the preferred test — it reflects folate status over the past 2–3 months (the lifespan of red blood cells), while serum folate changes rapidly with diet and supplements. The functional medicine community considers this a more reliable long-term marker. For MTHFR patients, functional practitioners target upper-normal or above. If supplementing with methylfolate, RBC folate will reflect your true tissue status better than serum. These notes reflect common practices in functional medicine communities.
Reflects common practices in thyroid, BHRT, and functional medicine communities. This may differ from standard clinical guidelines. Not medical advice — always discuss with your provider.
General guidelines only. Requirements vary by lab and individual. Confirm with your provider before adjusting any medications.
Turnaround Time
Varies by lab
Clinical Notes
More accurate indicator of tissue folate stores than serum folate
ICD-10 Codes
Common diagnosis codes associated with this test. Codes are assigned by your provider.
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Lab Codes
Proprietary codes used by each lab for this test.
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For informational purposes only
This page is for educational and research purposes only and does not constitute medical advice, diagnosis, or treatment recommendations. ICD-10 and CPT codes are assigned by your healthcare provider. Always consult a qualified healthcare provider before ordering any lab test or making decisions about your health.