[Proteins C and S of coagulation: new markers of thrombotic risk in nephrotic syndromes?].

: Thromboembolic events remain one of the most serious complications in patients with nephrotic syndrome (NS). The natural anticoagulant system protein C-protein S was evaluated in patients with proteinuria and NS. Protein C levels were found to be normal or increased in NS. Protein C levels correlated positively with proteinuria, cholesterol and triglycerides and negatively with serum albumin. All of the 17 patients with NS exhibited urinary loss of protein C. Total protein S and C4BP were increased in mild and moderate forms of NS. Free protein S was identical in controls and NS patients. Nine of ten patients had urinary loss of protein S. No correlation was found between protein S and the various usual biologic parameters of NS. However, two patients with NS and thrombosis of the renal veins had an acquired deficit in either free protein S or protein C. Thus, in some patients, an acquired deficit in free protein S and/or protein C may contribute to the development of thrombotic complications in NS.