title: Results of an international round robin for serum and whole-blood folate.
abstract: Because of the increasing significance of folate nutriture to public health, a "round robin" interlaboratory comparison study was conducted to assess differences among methods. Twenty research laboratories participated in a 3-day analysis of six serum and six whole-blood pools. Overall means, SDs, and CVs derived from these results were compared within and across method types. Results reported for serum and whole-blood folate demonstrated overall CVs of 27.6% and 35.7%, respectively, across pools and two- to ninefold differences in concentrations between methods, with the greatest variation occurring at critical low folate concentrations. Although results for serum pools were less variable than those for whole-blood pools, substantial intermethod variation still occurred. The overall results underscore the urgent need for developing and validating reference methods for serum and whole-blood folate and for properly characterized reference materials. For evaluating study or clinical data, method-specific reference ranges (established with clinical confirmation of values for truly folate-deficient individuals) must be used.
authors.affiliation: Division of Environmental Health Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Public Health Service, US Department of Health and Human Services, Atlanta, GA 30341-3724, USA.
authors.forename: E W
authors.initials: EW
authors.lastname: Gunter
authors.forename: B A
authors.initials: BA
authors.lastname: Bowman
authors.forename: S P
authors.initials: SP
authors.lastname: Caudill
authors.forename: D B
authors.initials: DB
authors.lastname: Twite
authors.forename: M J
authors.initials: MJ
authors.lastname: Adams
authors.forename: E J
authors.initials: EJ
authors.lastname: Sampson
mesh_terms: D000328:Adult; D001681:Biological Assay; D001774:Blood Chemical Analysis / Q000379:methods* / Q000592:standards*; D002851:Chromatography, High Pressure Liquid; D005260:Female; D005492:Folic Acid / Q000097:blood*; D006801:Humans; D007780:Lacticaseibacillus casei; D008163:Luminescent Measurements; D008280:Magnetics; D008297:Male; D011786:Quality Control; D011863:Radioimmunoassay; D012015:Reference Standards; D012016:Reference Values
chemical_list: D005492:Folic Acid