Background. Sirolimus is an immunosuppressive drug whose use is frequently associated with anemia. A pathogenic link between sirolimus-induced anemia and the appearance of an inflammatory state was recently suggested. Because inflammation-related anemia is characterized by a functional iron deficiency, we investigated whether sirolimus may influence iron homeostasis and serum levels of hepcidin, a key mediator of inflammation-related anemia.
Methods. To this purpose, 42 consecutive transplanted patients with biopsy-proven chronic allograft nephropathy were randomized (2:1 ratio) to receive either a 40% cyclosporine reduction (group A, 14 patients) or immediate cyclosporine withdrawal and sirolimus introduction (group B, 28 patients). Hemoglobin levels and iron status were evaluated 6 months before and after randomization.
Results. The two groups had similar hemoglobin levels and iron status at baseline. We did not observe any significant change in hemoglobin and iron status in group A patients after randomization. On the contrary, we observed a significant reduction of hemoglobin without any change of red blood cell count after sirolimus introduction, with a significant reduction of mean corpuscular volume and mean corpuscular hemoglobin. Serum iron and transferrin saturation (TSAT) levels were markedly reduced after the switch, while ferritin serum concentrations remained stable. Although sirolimus-induced anemia was recently suggested to resemble inflammation-related anemia, hepcidin serum levels were similar in the two groups after randomization. None of group A and eight of group B patients presented a TSAT <20 and were given iron supplementation after randomization, in all of them oral iron therapy did not influence either hemoglobin or serum iron levels.
Conclusion. We demonstrated that sirolimus-induced anemia is independent of the drug antiproliferative effect and does not present the features of inflammation-related anemia. This event may be due to the direct influence of sirolimus on iron homeostasis.
1 Division of Nephrology, Department of Emergency and Transplantation, University of Bari, Italy.
2 Division of Nephrology, Department of Biomedical Sciences, University of Foggia, Italy.
The study was partly supported by Ministero della Salute (to F.P.S.).
3 Address correspondence to: Giuseppe Grandaliano, M.D., Division of Nephrology, Department of Emergency and Transplantation, University of Bari, Piazza Giulio Cesare 11, 70124 Bari, Italy.
Received 5 January 2006. Revision requested 1 June 2006.
Accepted 8 June 2006.