Lupus anticoagulant confirmation testing was considered positive when the difference between both aPTT-LA clotting times was greater than 8 seconds ([aPTT-LA.sub.Difference], Staclot LA [Diagnostica Stago S.A.S, Asnieres sur Seine, France]) or the ratio between the neat diluted Russell viper venom time (dRVVT) and the [dRVVT.sub.Confirm] ([dRVVT.sub.Ratio], Staclot DRVV Screen/Staclot DRVV Confirm) was greater than 1.25.
b, [dRVVT.sub.Confirm] (diluted Russell viper venom time confirmation testing).
LAC was detected again on admission with the following results: kaolin clotting time greater than 200 seconds (normal range 100 to 160), dilute Russell Viper Venom
Time 96 seconds (normal range 0 to 45), Russell Viper Venom+Phospholipid Time 50 seconds (normal range 0 to 38) with a resultant dilute Russell Viper Venom/Russell Viper Venom+Phospholipid Time index of 1.3 (normal range 0 to 1.3).
The effect is more pronounced with reagents whose phospholipid content is relatively low (12) and may be greater with the kaolin clotting time (KCT) than with the dilute Russell viper venom test (dRVVT) (14).
The use of the dilute Russell viper venom time for the diagnosis of lupus anticoagulants.
Kaolin clotting time and dilute Russell viper venom time distinguish between prothromb-independent and beta 2-glycoprotein I-dependent anti phospholipid antibodies.
Laboratory data showed hemoglobin 33 g/L, leukocyte 23.6 x [10.sup.9]/L, a prolonged activated partial thromboplastin time [is greater than] 150 seconds (control [is less than]42 seconds) and prothrombin time of 26.1 seconds (control 14.0 seconds), International Normalized Ratios value = 3D 2.09, and the presence of lupus anticoagulant (LA) antibodies (prolonged Russell viper venom
time and confirmed by the STACLOT LA ELISA test, Reaads Medical Products, Inc.).
Rivaroxaban has been shown to prolong the prothrombin time, (7,8) activated partial thromboplastin time, (9) and dilute Russell viper venom time (DRVVT) (10) in a concentration-dependent manner, but measuring drug activity by chromogenic anti-Xa assay may be preferred.
High-phospholipid Russell viper venom reagents were correlated with rivaroxaban concentration but did not correlate better than chromogenic anti-Xa methods.
A, Correlation between Biophen (Aniara)-calibrated rivaroxaban levels and tandem liquid chromatography-mass spectrophotometry (LC-MS/MS) using 2 different high-phospholipid Russell viper venom confirmatory reagents: Precision Biologics method and Siemens LA2 method.
LA detection was performed on filtered plasmas according to the criteria of the Scientific and Standardization Committee (SSC) of the International Society on Thrombosis and Hemostasis (ISTH) (9) with screening and confirmatory procedures carried out with 3 tests: home-made silica clotting time (SCT), home-made and commercial dilute Russell viper venom
tests (dRVVT), and an activated partial thromboplastin time (APTT) with hexagonal phospholipids.