Influence of temperature and storage duration on measurement of activated partial thromboplastin time, D-dimers, fibrinogen, prothrombin time and thrombin time, in citrate-anticoagulated whole blood specimens.

INTRODUCTION: We report the effect of temperature and storage duration on a range of haematological analytes: activated partial thromboplastin time (APTT), D-dimers, fibrinogen (Fbg), prothrombin time (PT) and thrombin time (TT). All analytes were measured using a Sysmex CA7000 System with SIEMENS reagents.
METHODS: One hundred and sixty patients were divided into two groups: samples from group A (80 patients) were used to assess the effect of storage at room temperature (RT) (0, 4, 8 and 24 h), and samples from group B (80 patients) were used to determine the effect of storage at 4 °C. Percentage changes compared with baseline results (T = 0 result) were calculated, and clinically relevant differences were defined as a percentage change of >10%.
RESULTS: Changes in APTT, D-dimer, Fbg, PT and TT results following 4, 8 and 24 h storage were statistically significant at RT and 4 °C. For D-dimer, Fbg, PT and TT at both RT and 4 °C, the mean percentage changes after all storage periods were <10%, but for APTT, the mean percentage change following 24 h storage was >10% and exceeded the analytical within-batch imprecision.
CONCLUSION: We demonstrate that a storage time interval up to 24 h for D-dimers, Fbg, PT, and TT, and 8 h for APTT at either RT or 4 °C is acceptable.