title: Field-study screening of blood folate concentrations: specimen stability and finger-stick sampling.
abstract: We describe optimized procedures for field studies of blood folate concentrations by using finger-stick blood sampling and include relevant studies on blood folate stability. We introduce whole-blood folate adjustment using sample hemoglobin (folate/hemoglobin, nmol/g) as a novel and practical tool yielding accurate and precise results when blood volume or dilution is unknown. Red cell folate concentrations (nmol/L) of 11,887 Americans correlated well with hemoglobin-corrected whole-blood folate concentrations (r2 = 0.993; red cell folate = 0.347 x hemoglobin folate + 1 nmol/L), which supports the approach of using the mean cell hemoglobin concentration (g/L) to interconvert red cell and hemoglobin folate data. Folate concentrations in capillary (finger stick) and venous blood samples from 28 normal donors were similar (P > 0.87), correlating closely (r = 0.98, P < 0.001). Whole-blood samples (collected into K2-EDTA-containing evacuated tubes) in field studies are best stored intact at 4 degrees C until they can be processed and frozen (-20 degrees C). Specific knowledge of blood folate stability is essential in planning and designing field studies.
authors.affiliation: Department of Haematology, St James's Hospital, Dublin, Ireland.
authors.forename: S D
authors.initials: SD
authors.lastname: O'Broin
authors.forename: B P
authors.initials: BP
authors.lastname: Kelleher
authors.forename: A
authors.initials: A
authors.lastname: Davoren
authors.forename: E W
authors.initials: EW
authors.lastname: Gunter
mesh_terms: D001800:Blood Specimen Collection / Q000379:methods*; D005260:Female; D005385:Fingers; D005492:Folic Acid / Q000097:blood*; D006801:Humans; D008297:Male; D012044:Regression Analysis
chemical_list: D005492:Folic Acid