Acute renal failure after cardiopulmonary bypass is related to decreased serum ferritin levels

Acute renal failure (ARF) requiring dialysis occurs in up to 4% of patients after cardiopulmonary bypass (CPB). CPB leads to the generation of intravascular free hemoglobin, resulting in increased endothelial and renal tubular cell free Iron, which is associated with renal injury. Conversely, renogrotec tion is conferred by processes that upregulate heme and iron sequestration pathways, such as ferritin. This study evaluates the influence of free hemoglobin generation during CPB and the capacity to sequester free iron on the occurrence of post-CPB renal insufficiency. Thirty consecutive patients undergoing CPB were enrolled in the study. Serum creatinine, free hemoglobin, and ferritin were measured preoperatively, at the end of bypass, and 24 and 48 h after surgery. Renal injury, as determined by an increase in the serum creatinine greater than or equal to 25% (ARF) by 48 h after surgery, occurred in 40% (12 of 30) of patients, and dialysis was necessary in 6.6% (2 of 30). Free hemoglobin levels increased in all patients but did nor correlate with postoperative ARF. However, patients with preoperative serum ferritin levels less than or equal to 130 mu g/L, the median value for the group, had a six fold greater likelihood of developing ARF compared to patients with levels above this value (P = 0.03). Lower serum ferritin levels appear to be associated with the development of ARF. Serum ferritin levels may signify intravascular: as well as endothelial and renal epithelial cell ability to bind free iron generated during CPB-induced hemolysis, and thus may help provide information regarding the risk for ARF.