[Thrombotic complications in the nephrotic syndrome]

Thromboembolic episodes are one of the most serious complications in patients with nephrotic syndrome, with an overall incidence of 25%. The most frequent site of thrombosis is the renal vein, with a reported incidence varying from 2-42%. Arterial thromboses are much less common than venous thromboses, with an overall incidence of 3%. Clinical course of renal vein thrombosis may be acute or chronic. Renal venography is the method of choice in its diagnosis. Duplex scanning, computed tomography and magnetic resonance imaging may be as accurate as venography. Once the diagnosis of renal vein thrombosis is established, anticoagulation therapy should be started. Thrombectomy or thrombolytic therapy seem to have little to offer over oral anticoagulation. The increased incidence of thrombotic complications in nephrotic syndrome may be due to a hypercoagulable state distinguished by an increase in coagulation factors (V, VIII, X and fibrinogen); a decrease in the levels of coagulation inhibitors (antithrombin III, protein S); an increase in alpha 2-antiplasmin activity; and exaggerated platelet adhesiveness and aggregation. This pre-thrombotic state may be aggravated by additional rheological factors (immobilization, diuretic therapy etc.). Serum albumin has been found to be an appropriate parameter to assess the risk of thrombosis development in these patients. A serum albumin level below 20 g/l carries a high risk of thromboembolic complications. Prophylactic anticoagulation therapy is therefore indicated in patients with serum albumin below 20 g/l.