Effect of pre-analytical variables on glycohemoglobin measurements in routine clinical care

Objectives: To analyze the contribution of the labile A1C fraction (L-A1C) and sample storage conditions on GHb measurements. Design and methods: L-A1C separation (HPLC Hitachi L-9100) was evaluated before and after sample treatment by four different methods for L-A1C removal. Different sample storage conditions were analyzed. Results: L-A1C may overestimate up to 1.64% total A1C if not properly separated. Samples were stable for up to 10, <1, and at least 100 days for whole blood stored at 4, −20, and −80 °C, respectively. Conclusions: The presence of L-A1C may overestimate GHb results. Samples may be kept under refrigeration up to 10 days and at −80 °C if long-term storage is required.