B-097 Storage Stability of HbA1c in Whole Blood Tubes at Room Temperature on the Abbott Alinity c Clinical Chemistry System

Abstract

Abstract Background Hospital laboratories frequently receive requests to order additional tests on an existing specimen. For this reason, laboratories routinely save specimens after initial testing has been completed for a defined period of time. The current literature lacks specific information regarding HbA1c stability in whole blood and the effects of red blood cell settling. In addition, literature references are not inclusive of various conditions which can cause gaps in data collection such as samples in queue for prolonged periods. To obtain information on prolonged storage of whole blood tubes, HbA1c was assessed for storage at room temperature (RT) (20–25°C) for up to 4 hours on the Alinity c system. In addition, potential carryover from a whole blood to a serum sample was assessed. Methods A minimum of 40 whole blood sample pools (approx. 8 mLs) were prepared from remnant samples. Sample pools were mixed, aliquoted, and stored at RT on the Alinity c system. The samples were tested as a single replicate continuously for up to 4 hours without mixing (minimum of 20 cycles) and compared to the baseline sample values. Carryover from a whole blood to a glucose serum sample was assessed after 4 hours continuous testing of whole blood to mimic a high volume testing laboratory. The stability of each HbA1c sample and carryover into a glucose sample were evaluated by comparing the mean absolute or percent difference from the respective sample baseline measurement. The allowed deviation from baseline was 5%. Results After 4 hours at RT, the whole blood cells had settled to approximately 50% from the top of the tube. The red blood cell settling had no significant impact on the results. Within sample precision for the 20 cycles of repetitive testing was </ = 1%. The 48 individual samples showed insignificant difference from the baseline value, with a mean change of 1.0% (Range 0–3.2%). Sample carryover from the whole blood samples to a serum glucose sample was not significant (2.71 Baseline vs 2.64 first replicate). Conclusion This study demonstrated that the storage stability of HbA1c is stable for up to 4 hours at RT on the Alinity c system.