LMW heparin (anti-Xa) assays for clinical monitoring and pharmacokinetic studies on the automated coagulation laboratory (ACL).
Chromogenic anti-Xa activity procedures were developed for monitoring LMW heparins on the Automated Coagulation Laboratory 300 Plus (ACL, Instrumentation Laboratory) system. For daily monitoring, a "Routine" procedure was devised which allows accurate measurements between plasma levels of 0.1 and 1.0 u/ml LMW heparin. For lower levels a "Routine-Low" method was developed which assesses activities between 0.05 and 0.4 u/ml. Due to variabilities in dODs of individual baseline plasmas, levels below 0.05 u/ml might be inaccurate when pooled normal plasma is used to establish the reference curve. While levels less than 0.05 u/ml should rarely be encountered when monitoring LMW heparins for routine clinical use, pharmacokinetic studies require accurate measurements below that level. For this reason a "Research-High" and a "Research-Low" procedure was designed. For these procedures a study subject's own baseline plasma was used to establish the reference curve. The "Research-High" measures activities between 0.4 and 2.0 u/ml, the "Research-Low" between zero and 0.4 u/ml. The procedures have excellent within-run and inter-run coefficients of variation (less than 5%) and high levels of accuracies. Even inter-instrumental reproducibilities are less than 10%. Different manufacturers' LMW heparins can be analyzed by these assays. The procedures offer full automation, great cost-effectiveness due to lower reagent volumes, rapid turn-around time and great accuracy and reproducibility.
Ozawa
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Department of Pathology, Wayne State University School of Medicine, Detroit, Michigan 48201.
Mammen
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D000990:Antithrombin III / Q000378:metabolism; D001331:Automation; D001780:Blood Coagulation Tests / Q000295:instrumentation*; D002863:Chromogenic Compounds; D065427:Factor Xa Inhibitors; D006495:Heparin, Low-Molecular-Weight / Q000097:blood* / Q000493:pharmacokinetics / Q000494:pharmacology; D006801:Humans; D008838:Microcomputers; D009842:Oligopeptides; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D002863:Chromogenic Compounds; D065427:Factor Xa Inhibitors; D006495:Heparin, Low-Molecular-Weight; D009842:Oligopeptides; D000990:Antithrombin III; C049024:H-hexahydrotyrosyl-alanyl-arginine-4-nitroanilide