Effect of Storage Time on Prothrombin Time and Activated Partial Thromboplastin Time Test on Abnormal Specimens

Objective To investigate the effect of storage time on prothrombin time(PT) and activated partial thromboplastin time(APTT) at room temperature under the condition of coagulation disorder.Methods Clinical specimens with normal and prolonged storage time on PT and APTT tests were enrolled.The assay was conducted immediately after centrifuge,and PT of 11.0-14.3 s and APTT of 32.0-43.0 s were considered as the normal range.The specimens were kept at room temperature,and the coagulation test was performed at 1 h,2 h,4 h,6 h,8 h,12 h,24 h after collection.Results For normal specimens,PT result was stable up to 8 h,APTT up to 4 h at room temperature;but for the prolonged storage time,PT was stable up to 4 h,APTT 2 h.Conclusion Normal specimens were stable at 4 h for coagulation tests,but the coagulation assays should be performed in 2 h for the prolonged group was stable for only 2 h.