Objective This study was designed to determine the in vitro effects of different doses and different kinds of Low Molecular Weight Heparin (LMWH) on clot rate (CR), and to determine whether the CR can be used to monitor LMWH.
Methods This study was performed in two phases in vitro. The first, CR was measured with different reagent (glass beads, celite and kaolin) on volunteer (n=20) blood samples spiked with increasing concentrations of LMWH (dalteparin, 0.2–1.8 IU/ml). The second, CR were measured with the same reagent (glass beads) on volunteer (n=20) blood samples spiked with the same concentrations (0.8 IU/ml) of different LMWH (dalteparin, enoxaparin and nadroparin). Regression analysis was performed to establish a regression equation from corresponding anti-Xa LMWH levels.
Results With the increase in doses of dalteparin, CR values were reduced gradually and an exponential relationship was observed between the CR values and dalteparin concentrations (p<0.01) for all three reagents. With the same concentrations (0.8 IU/ml) of LMWH, dalteparin showed a more effect on CR (dalteparin 7.4 IU/min vs enoxaparin 8.5 IU/min, nadroparin 8.5 IU/min, p<0.05). Compare with the baseline (17.6 IU/min), all three kinds of LMWH induced a significant change in the CR (p<0.01).
Conclusions The in vitro studies have shown that, there was an exponential relationship between the CR and dalteparin concentrations for all three reagents. All three kinds of LMWH could significantly reduce the value of CR. CR test may be a suitable method for monitoring the anticoagulant effect of LMWH.
- Clot rate
- low molecular weight heparins