Using an Anti-Xa assay
to monitor UFH has reduced blood transfusions by 4.
The American College of Chest Physicians approved use of the anti-Xa assay
(Garcia, Baglin, Weitz, & Sanama, 2012).
Evaluate the local utility and practicality of validating currently available methods to quantify the anticoagulant activity of DTI (dilute thrombin time or ecarin time calibrated with dabigatran) and DFXaI (chromogenic anti-Xa assay
calibrated with rivaroxaban or apixaban).
The anti-Xa assay
is currently available for enoxaparin and nadroparin at the Charlotte Maxeke Johannesburg Hospital NHLS haematology laboratory ((011) 488-3068 or (011) 489-8534) as well as in private laboratories.
LMWH levels cannot be monitored by the aPTT, but require a specialised anti-Xa assay
, which is currently available at Johannesburg Hospital Haematology Laboratory (tel (011) 488-3068).
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.
INR responses vary widely depending on the thromboplastin assay reagent, but a calibrated anti-Xa assay
appears to be a suitable method for determination of Riva concentration (13-16).