Q: Should you test folate levels in your anemic patients?

The Bottom Line: Do NOT routinely test folate levels in your anemic patients.

Context: Folate deficiency is a well-described cause of macrocytic anemia. The American diet has been fortified with folate from a variety of food sources since 1998. This has led to near-elimination of folate deficiency (less than 1 in 1000 prevalence in a large North American cohort1).

The Data: Two large, hospital-based retrospective cohort analyses found 20932 and 25633 inpatient RBC folate levels assessed in a one year period, respectively. Only two and four individuals, respectively, were found to have deficient levels on testing, and one of the low levels in the second study was actually felt to be spurious. The cost of folate testing in these studies ranged from $32,000 to $316,000, with a cost per deficient result ranging from $8,000 to $158,000.

Conclusion: Folate deficiency is vanishingly rare in North American patients and only seen in specific contexts: severe alcohol use disorder, malabsorption, severe malnutrition, etc.

  1. Am J Clin Nutr. 2013 Oct;98(4):1042-7 PMID: 23945721
  2. J Hosp Med. 2013 Feb;8(2):91-5 PMID: 23169580
  3. Am J Med. 2014 Sep 4. pii: S0002-9343(14)00784-0 PMID: 25196989

Written by Alexander Billioux, MD DPhil for the Department of Medicine High Value Care Committee

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