Clinical evaluation of a new one-stage clotting assay for heparin and low molecular weight heparins.

Heptest, a new one-stage clotting assay was compared with the anti-factor Xa chromogenic substrate S 2222 method, the thrombin clotting time (TCT), and the activated partial thromboplastin time (aPTT) tests in 100 patients receiving unfractionated mucosal heparin, and 100 patients treated with Kabi 2165 low molecular weight heparin. The results indicate a high correlation between the Heptest and the anti-Xa chromogenic substrate method (r = 0.91 for unfractionated heparin, and 0.90 for Kabi 2165 low molecular weight heparin). The correlations between the Heptest and the aPTT were 0.36 for unfractionated heparin, and 0.14 for low molecular weight heparin, while those of the TCT were 0.36 and 0.27, respectively. The test is a very sensitive, simple, highly reproducible and reliable clotting assay for unfractionated and low molecular weight heparins in plasma.