Objective: To explore the sensitivity of new activated clotting time (ACT) reagent for laboratory monitoring of low molecular weight heparin (LMWH).
Methods: Blood samples were collected from 30 healthy volunteers and different doses of LMWH (dalteparin) added. The dalteparin concentration of final blood samples was 0.1 - 1.8 U/ml. ACT and clot rate (CR) were measured with traditional reagent kaolin and new reagent magbar. Linear regression analysis was performed and a regression equation established between different dalteparin concentrations and their corresponding ACT and CR values.
Results: With rising dalteparin concentrations, the ACT values became gradually extended and the CR values were gradually reduced by both kaolin and magbar. Analysis of dose-response curves was obtained in vitro. And an excellent linear relationship was observed between the ACT and dalteparin concentrations for two reagents (P < 0.01). An exponential relationship was observed between the CR and dalteparin concentrations (P < 0.01). Differences in slope of regression curves of ACT were observed with the tested reagents (magbar 1097.6 s/U vs kaolin 59.3 s/U, P < 0.01).
Conclusion: This in vitro study has shown that the sensitivity of new ACT test reagent (magbar) is good for laboratory monitoring of dalteparin. The new reagent magbar may be used for bedside monitoring of anticoagulant activity of LMWH.