Publication Date:
2005-11-16
Description:
Abnormalities of the protein C (PC) anticoagulant pathway i.e. PC deficiency, PS deficiency and APC-resistant factor Va (FV Leiden) are among the most frequent biological risk factors for venous thromboembolism (VTE) in Caucasian patients but normal results are found in more more than 70% of the cases. This highlights the potential usefulness of a simple assay to screen globally for these abnormalities as this would rationalize the use of expensive individual assays. The HemosIL Thrombopath (Instrumentation Laboratory) is a new chromogenic global assay based on the ability of endogenous APC generated after activation of PC by a snake venom (Protac) to reduce the thrombin generation induced by a reagent containing tissue factor. Optical density is measured after addition of a thrombin-specific chromogenic substrate in the presence (OD A) or absence (OD B) of Protac. It is recommended by the test manufacturer to express results as the Protac-Induced Coagulation Inhibition percentage (PCI%) which corresponds to the ratio [OD B - OD A]/OD B x 100. The assay was performed on the ACL9000 analyzer (IL) using 85% as the cut-off level (PCI%) as we previously determined. Using various lyophilized plasma samples (n=8) both in the normal and abnormal ranges, the within-run precision (evaluated as the CV%, n=17) was found in the range from 1.2% to 2.8% and the between-run precision (CV%, n=48) in the range from 1.6% to 6.3%. The assay sensitivity for PC pathway abnormalities was studied by evaluating a selection of frozen plasma samples from 144 patients with a history of VTE (to be expended). All patients with FV Leiden, PC deficiency (1 with a borderline value), combined defects and lupus anticoagulant (LA) had a decreased response to the assay (PCI%
Print ISSN:
0006-4971
Electronic ISSN:
1528-0020
Topics:
Biology
,
Medicine
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