PB1161 - Evaluation of three Prothrombin Time reagents and their sensitivity to extrinsic pathway factor deficiencies (FII, FV and FVII)

Background: The Prothrombin Time is used as a screening test for deficiencies of factor II, V and VII. Prothrombin Time (PT) reagents may demonstrate different sensitivities to these clotting factors.

Aims: To compare three new PT reagents, YUMIZEN G PT 5, G PT Liq 4, G PT Reco 5, with STA NeoR , STA NeoPTimal, to detect factor deficiencies in the extrinsic pathway (FII, FV and FVII) on analyzer Yumizen G1550.

Methods: For factor II, V and VII, dilutions were prepared from Standard Human Plasma (SHP, Siemens) and the respective deficient- factor plasmas (Stago). Eleven dilutions was realized to achieve plasmas with factor concentration of 0-100 UI/dL. PT tests were performed on each sample with the 5 PT reagents in duplicate on HORIBA Yumizen G1500. The Mean Normal Prothrombin Time (MNPT) has been evaluated for each reagent on each instrument using the CRYOcheck™ Normal Donor Set. PT ratio were calculated by dividing the PTs by the MNPTs. For each PT reagent, the intersection of the 1.2 PT ratio (upper limit reference range) and the concentration of clotting factor determined the reagent sensitivity to each factor.

Results: Sensitivity to FII range from 14 to 65 UI/dL, to FV from 20 to 40 UI/dL and to FVII from 27 to 80 UI/dL (G PT Reco 5- STA NeoPTimal for the 3 factors). Sensitivity to FVII is greater than 27 UI/dL for the 5 PT reagents. Sensitivities of the G PT Liq 4 is from 32 UI/dl to 50 UI/dl for the 3 factors (FII-FVII).

Conclusion(s): The 3 PT reagents from Yumizen tested perform satisfactorily for the detection of FII, FV and FVII deficiency. Their sensivity to FVII deficiency is clinically relevant. The G PT Liq 4 seems to be most interesting, because of its sensitivity for the 3 factors and its practicality (ready-to-use reagent).