Laboratory Monitoring of Low-Molecular-Weight Heparin and Fondaparinux.

Compared with older agents, low-molecular-weight heparins (LMWH) and fondaparinux offer improved bioavailability and more predictable, dose-independent clearance. While routine monitoring of coagulation parameters is not usually necessary with these agents, certain populations (including pregnant patients, children, obese patients, and patients with renal impairment) may benefit from the monitoring of anti-factor Xa activity, thromboelastography, or other coagulation assays to help guide therapy. The chromogenic anti-factor Xa assay is currently the gold standard for monitoring LMWH and fondaparinux therapy. Thromboelastography has been used to monitor LMWH therapy in special situations but is not needed for routine use.