Three different chromogenic methods do not give equivalent anti-Xa levels for patients on therapeutic low molecular weight heparin (dalteparin) or unfractionated heparin.
In this study we compare three chromogenic methods (IL-Heparin, Stachrom Heparin and Heparin Sigma) on two different instruments (ACL300+ and AMAX CS190) for patients on dalteparin (n = 41), a low molecular weight heparin or unfractionated heparin (n = 50). For dalteparin the mean anti-Xa levels for IL-Heparin, Stachrom Heparin and Heparin Sigma were 0.27, 0.30 and 0.21 U/ml, respectively, while for heparin they were 0.52, 0.55 and 0.41 U/ml, respectively. To test for instrument specific effects, IL-Heparin and Stachrom Heparin were repeated on both instruments on 42 patients receiving unfractionated heparin. For IL-Heparin the mean anti-Xa levels on the AMAX CS190 and ACL300+ were 0.51 and 0.59 U/ml, respectively, while for Stachrom Heparin they were 0.55 and 0.67 anti-Xa U/ml. We conclude that different chromogenic anti-Xa methods do not give equivalent anti-Xa levels for the same samples. Moreover, the differences are clinically significant. This is not explained entirely by instrumentation effects. Recommended therapeutic ranges may need to be method and instrument specific.
Kovacs
M J
MJ
London Health Sciences Centre, Ontario, Canada.
Keeney
M
M
MacKinnon
K
K
Boyle
E
E
D000704:Analysis of Variance; D000906:Antibodies / Q000097:blood; D002863:Chromogenic Compounds; D004305:Dose-Response Relationship, Drug; D015951:Factor Xa / Q000276:immunology*; D065427:Factor Xa Inhibitors; D006493:Heparin / Q000627:therapeutic use*; D006495:Heparin, Low-Molecular-Weight / Q000627:therapeutic use*; D006801:Humans; D020246:Venous Thrombosis / Q000188:drug therapy
D000906:Antibodies; D002863:Chromogenic Compounds; D065427:Factor Xa Inhibitors; D006495:Heparin, Low-Molecular-Weight; D006493:Heparin; D015951:Factor Xa