Abstract
BACKGROUND: Hemoglobin A1c (HbA1c) has been endorsed as a tool for the diagnosis of diabetes. This test requires instrumentation that may not be available in underdeveloped areas. Dried blood spot (DBS) samples collected by finger stick procedures offer a mechanism to transport samples to laboratories that do measure HbA1c. METHODS: Whole blood (ethylenediaminetetraacetic acid) was applied to Ahlstrom 226 filter paper. These DBS samples were compared to whole blood samples using the Roche Tina-quant II immunoturbidometric assay. Hemoglobin A1c stability on DBS was assessed at three temperatures-4, 25, and 40 degrees C-for up to 9 days. A 44-day study was also done for DBS at 20-25 degrees C. RESULTS: The Tina-quant II DBS method showed excellent agreement with whole blood HbA1c results (r(2) = 0.99) with a slight positive mean bias of 0.08 +/- 0.04% HbA1c (95% confidence interval). The variation in HbA1c on DBS samples subjected to different temperatures and times did not exceed 5.6%. CONCLUSIONS: Dried blood spot samples represent an alternative to whole blood for HbA1c by measurement when transporting whole blood is not feasible.