Abstract: Objective To verify the measurement performance of low molecular weight heparin（LMWH） anti-Ⅹa activity assay,antithrombin（AT）activity assay and activated partial thromboplastin time （APTT） test. Methods According to the Clinical and Laboratory Standards Institute （CLSI） guidelines,the professional standards and manufacturer's instructions,the performance characteristics of LMWH anti-Ⅹa activity assay,AT activity assay and APTT test were verified as follows： within-run precision,between-day precision,linearity,accuracy or comparability and the limit of detection （LoD,only for LMWH anti-Ⅹa activity assay）. Results The within-run precision,between-day precision,linear range,bias for accuracy and LoD of LMWH anti-Ⅹa activity assay were 0.03 anti-Ⅹa IU/ml and 0.05 anti-Ⅹa IU/ml,0.04 anti-Ⅹa IU/ml and 0.05 anti-Ⅹa IU/ml,0-1.83 anti-Ⅹ a IU/ml,4.3% and 2.2%,0.05 anti-Ⅹa IU/ml,respectively,all of which were acceptable following manufacturer’s instructions. The within-run precision,between-day precision,linear range and bias for accuracy of AT activity assay were 2.0% and 3.5%,2.7% and 5.3%,0%-139%,0.9%,-1.4% and -2.7%,respectively,all of which were acceptable following manufacturer's instructions. The within-run precision,between-day precision and bias for comparability of APTT test were 0.5% and 0.4%,3.4% and 4.4%,within ±15.0%,respectively,all of which were acceptable according to professional standards and manufacturer's instructions. Conclusion The verified data of the LMWH anti-Ⅹa activity,AT activity and APTT detection systems were acceptable according to the professional standards and manufacturer's instructions. It is very important to set up the Methods and specifications of verification for clinical laboratories to implement quality improvement.

Key words: Heparin, Laboratory monitoring, Anti-Ⅹa activity, Antithrombin, Performance verification