Determination of low-molecular-weight heparin by Heptest on the automated coagulation laboratory system.

Abstract

The manual Heptest for measuring low-molecular-weight heparin fractions was applied to a fully automated, coagulation-dedicated analyzer, the Automated Coagulation Laboratory 300 Plus. The clot-based assay mode of the instrument was used, which operates on the principle of light scattering. Undiluted plasmas and the original reagents of the Heptest kit were used. Also, the 2-minute incubation time of the manual procedure was maintained. Automation reduced plasma and reagent volumes by about one half. As a result of the high precision of the automated procedure, single determinations suffice, and 18 plasma samples can be analyzed in about 8 minutes. Coefficients of variation were 1.0% to 3.2% for within-run and 1.9% to 6.0% for inter-run analyses. Analytical recovery was 98% to 104%. Comparisons of 132 samples between the two procedures yielded an R value of 0.974 for activity expression in seconds and 0.945 for U/mL. Several low-molecular-weight heparin fractions were tested.