Fully automated Anti-Xa assays
permit routine labs to easily monitor UFH.
Advantages of the anti-Xa assay
include achievement of therapeutic goal within 24 hours or less, fewer dosage adjustments and laboratory tests reducing the potential for titration errors, and saved nursing time (Fruge & Lee, 2015).
Rivaroxaban: anti-Xa assay
utilising a specific rivaroxaban calibrator
Recommendations for monitoring patients on LMWH (South African Society of Thrombosis and Haemostasis 2004) (4) * The patient's platelet count should be checked on initiation of LMWH, after 5 days, and thereafter not less than once every 3 months, while on therapy * Anticoagulant activity is measured using an anti-Xa activity assay * Anti-Xa measurement is only indicated in pregnancy, renal failure or in excessively obese patients in whom large doses are required * The anti-Xa assay
must be calibrated for each LMWH tested * The anti-Xa assay
is available for enoxaparin and nadroparin at Johannnesburg Hospital Haematology Laboratory, tel (011) 488-3068 or (011) 489-8552 * 5 ml citrated blood taken 3 hours after a LMWH dose is required for the assay Target levels: Prophylaxis target: 0.
Currently, the chromogenic anti-Xa assay
is the preferred assay for measuring plasma rivaroxaban concentrations in the clinical laboratory.
In addition, calibrators with Riva concentrations of 0, 15, 60, 100, and 150 [micro]g/L were sent to 18 Finnish laboratories for the local anti-Xa assay
5) This article also includes a discussion of the preferred method of monitoring LMWH by chromogenic anti-Xa assay