[Immunologic determination of the protein C of coagulation: detection of deficiencies].

Protein C, discovered by Stenflo in 1976, plays a major role in the regulation of thrombogenic processes. Even moderate deficiencies (0.40 to 0.60 U/ml) can be responsible for serious thromboembolic accidents. The authors evaluated the kits for the immunological assay of protein C, produced by Laboratoire Diagnostica Stago: a immuno-enzymatic method (ELISA) and Laurell's method. Despite the very different characteristics in terms of practicability, threshold of sensitivity and precision, the authors obtained an excellent correlation between these two techniques. The concentrations of protein C Ag obtained in 22 normal plasmas were 0.70 to 1.40 U/ml. In 32 patients with recurrent thrombosis with no apparent cause, 5 had a concentration of protein C Ag less than 0.70 U/ml. The identification of a deficiency of protein C Ag (Vitamin K depend protein) is often made difficulty by the fact that the patients are treated with anti-vitamin K drugs. The ratio between the vitamin K depend pro-coagulation factors and Protein C Ag may provide information about a possible deficiency.