Adopting an Evidence-Based Approach for Folate Testing in a Tertiary Care Center

Abstract

Abstract Plasma folate is a very commonly ordered test, despite evidence that folate deficiency is extremely rare following universal fortification of grains mandated in the United States in 1998. The objective of our study was to adopt an evidence-based approach for plasma folate testing and identify in what clinical and hospital settings folate may be an informative test. We performed a retrospective laboratory information system/patient chart review between 10/31/17 and 10/31/18 and identified folate-deficient patients. Folate testing data were collected over a 1-year period from a tertiary care hospital and associated allied centers. Data included total tests ordered, age and gender of patient, location of where testing was performed, plasma folate, vitamin B12, hemoglobin, and mean corpuscular volume (MCV). In addition, we looked at association in folate-deficient patients with history of alcohol use, immigrant status, gastric surgery, birth defects, and if any presented with neurological symptoms. Associated patient comorbidities and therapeutic interventions to treat folate deficiency were also noted. Our results show that 14,542 total tests were ordered during this time period, from which 408 patients (2%) had folate below the reference range of 5 ng/mL, with only 92 (0.6%) patients having results below 3 ng/mL (true folate deficiency). Five ICU patients were folate deficient, none of whom was below 3 ng/mL. The average age of folate-deficient patients was 58.3 (age range: 7-97), with a female predominance of 251 patients (61.5%). Hemoglobin results showed only 21 (5%) patients with values less than 7 g/dL, with 231 (56%) patients showing normal and 142 (34.8%) patients showing elevated MCV values (mean MCV: 93.1 fL, SD: 10.2). No clinically relevant association between concurrent folate deficiency and comorbid conditions was identified. Concurrent vitamin B12 testing performed in these patients showed normal levels in 299 (73.2%), while 27 (6%) and 70 (17%) patients showed B12 deficiency and elevation, respectively. Interestingly, only 176 (43%) of patients subsequently received folate supplementation. Our study highlights that folate testing following mandatory grain fortification is almost nonexistent. In addition, the vast majority of folate tests ordered provided no additional clinical information, particularly in the inpatient setting. In addition, our data suggest that elevated MCV values should not be used as a marker to suspect a diagnosis of folate deficiency. Folate testing should therefore be reserved for severely anemic patients without a clear etiology for anemia; however, even in this patient population, supplementation rather than testing may be a more effective option.