Zia Fazili1, Maya R Sternberg, Christine M Pfeiffer. 1. Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA 30341, United States.
Abstract
BACKGROUND: Limited information is available on folate stability, particularly vitamer stability by 5,10-methylenetetrahydrofolate reductase (MTHFR) C677T genotype, during frozen storage, thawing, and repeated freeze/thawing (F/T) of whole blood (WB). METHODS: We assessed folate stability after storing undiluted WB for up to 30 mo at -70°C and measuring folate vitamers by LC-MS/MS at 6, 14, 20 and 30 mo in samples with C/C and T/T genotype (n=13 each). We investigated folate stability during 3-h thawing of WB (n=2 each/genotype) and during repeated F/T of WB (n=4 each/genotype). RESULTS: We found significant decreases in total folate (TFOL) (median decrease: 8.8% for C/C and 16% for T/T), methyl folate (7.9% for C/C and 10% for T/T), and non-methyl folate (19% for C/C and 24% for T/T) concentrations from 6 to 30 mo WB frozen storage. During thawing of WB at room temperature and repeated F/T, samples with T/T genotype were susceptible to greater folate losses than samples with C/C genotype. CONCLUSIONS: Long-term frozen storage of WB resulted in significant folate losses of ~10-25% that are clinically unacceptable. Frozen WB should not be exposed to more than 1h of thawing time and repeated F/T of WB should be avoided. Published by Elsevier B.V.
BACKGROUND: Limited information is available on folate stability, particularly vitamer stability by 5,10-methylenetetrahydrofolate reductase (MTHFR) C677T genotype, during frozen storage, thawing, and repeated freeze/thawing (F/T) of whole blood (WB). METHODS: We assessed folate stability after storing undiluted WB for up to 30 mo at -70°C and measuring folate vitamers by LC-MS/MS at 6, 14, 20 and 30 mo in samples with C/C and T/T genotype (n=13 each). We investigated folate stability during 3-h thawing of WB (n=2 each/genotype) and during repeated F/T of WB (n=4 each/genotype). RESULTS: We found significant decreases in total folate (TFOL) (median decrease: 8.8% for C/C and 16% for T/T), methyl folate (7.9% for C/C and 10% for T/T), and non-methyl folate (19% for C/C and 24% for T/T) concentrations from 6 to 30 mo WB frozen storage. During thawing of WB at room temperature and repeated F/T, samples with T/T genotype were susceptible to greater folate losses than samples with C/C genotype. CONCLUSIONS: Long-term frozen storage of WB resulted in significant folate losses of ~10-25% that are clinically unacceptable. Frozen WB should not be exposed to more than 1h of thawing time and repeated F/T of WB should be avoided. Published by Elsevier B.V.
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