De novo hemolytic-uremic syndrome/thrombotic microangiopathy in renal transplant patients receiving calcineurin inhibitors: role of sirolimus.

The aim of this study was to evaluate the outcome of ten renal transplant recipients who developed de novo hemolytic uremic syndrome/thrombotic microangiopathy (DnHUS) after treatment with calcineurin inhibitors among 3,862 patients transplanted during the period 2000-2001 in Spain, and the results of switching to sirolimus for resolution of this pathologic condition. No patient had end-stage disease due to primary HUS. The criteria of diagnosis were decreased renal function, biopsy-proven thrombotic microangiopathy, and no signs of acute rejection. Calcineurin inhibitors were completely removed and immediate treatment with sirolimus started after diagnosis. The follow-up period was 19.0+/-4.3 months, at least 12 months after diagnosis. One patient died of sepsis shortly after starting sirolimus therapy. The serum creatinine level in the series decreased from 5.2+/-2.6 mg/dL at the time of biopsy to 2.15+/-1.9 mg/dL 1 month later (P=.011). All but one of the nine recipients, who lost his graft 3 months later (80% success) maintained function, with a serum creatinine of 2.1+/-1.4 mg/dL and Cockroft index of 61.3+/-34 mL/min at the end of follow up. During this time, none of the patients experienced an acute rejection episode and sirolimus was maintained without any remarkable secondary effect. Sirolimus seems to be a promising alternative for the treatment of renal transplant patients who develop calcineurin inhibitor-induced DnHUS.