RESISTANCE TO ACTIVATED PROTEIN-C MIMICKING DYSFUNCTIONAL PROTEIN-C -DIAGNOSTIC-APPROACH

It has been reported that resistance to activated protein C interferes with functional plasma-based coagulation assays of protein C, mimicki ng a type II deficiency. In this study we confirm and extend these fin dings. In our laboratory approximately 25% of patients with resistance to activated protein C have an apparent type II protein C deficiency. It is important for rapid and accurate diagnosis to be able to confir m or exclude a dysfunction of protein C associated with resistance. We therefore propose a new coagulation assay that requires first adsorpt ion of protein C from plasma, activation with a snake venom and measur ement of its anticoagulant activity. This assay is quick, reproducible and fan be automated. It is also insensitive to the presence of resis tance to activated protein C and allows detection of all types of prot ein C deficiency. This is important when screening for inherited cause s of thrombophilia since more than one defect might be present and int erference from resistance to activated protein C is common.