Optimizing centrifugation of coagulation samples in laboratory automation.

ABSTRACT

BACKGROUND: High acceleration centrifugation conditions are used in laboratory automation systems to reduce the turnaround time (TAT) of clinical chemistry samples, but not of coagulation samples. This often requires separate sample flows. The CLSI guideline and manufacturers recommendations for coagulation assays aim at reducing platelet counts. For measurement of prothrombin time (PT) and activated partial thromboplastin time (APTT) platelet counts (Plt) below 200×10(9)/L are recommended. Other coagulation assays may require even lower platelet counts, e.g., less than 10 × 10(9)/L. Unifying centrifugation conditions can facilitate the integration of coagulation samples in the overall workflow of a laboratory automation system. METHODS: We evaluated centrifugation conditions of coagulation samples by using high acceleration centrifugation conditions (5 min; 3280×g) in a single and two consecutive runs. RESULTS of coagulation assays [PT, APTT, coagulation factor VIII (F. VIII) and protein S] and platelet counts were compared after the first and second centrifugation. RESULTS: Platelet counts below 200×10(9)/L were obtained in all samples after the first centrifugation and less than 10 × 10(9)/L was obtained in 73% of the samples after a second centrifugation. Passing-Bablok regression analyses showed an equal performance of PT, APTT and F. VIII after first and second centrifugation whereas protein S measurements require a second centrifugation. CONCLUSIONS: Coagulation samples can be integrated into the workflow of a laboratory automation system using high acceleration centrifugation. A single centrifugation was sufficient for PT, APTT and F. VIII whereas two successive centrifugations appear to be sufficient for protein S activity.