Transfusions of older RBCs result in laboratory values consistent with extravascular hemolysis in healthy volunteers. Data are mean ± SEM for serum levels of (A) total bilirubin and (B) conjugated bilirubin from before transfusion to 72 hours after transfusion of both fresh and older RBCs. (C) The individual serum total bilirubin levels for all 14 volunteers from before transfusion to 72 hours after transfusion of both fresh and older RBCs. (D) Data are mean ± SEM for lactate dehydrogenase (LDH) and haptoglobin, from before transfusion to 72 hours after transfusion of both fresh and older RBCs. Although iatrogenic hemolysis was induced during a difficult blood draw for 2 volunteers at 1 hour after the older RBC transfusion, these samples were still included in the analysis; nonetheless, the analysis was not significantly altered by their exclusion. Vertical arrows in all panels indicate the pretransfusion time point; and dotted lines, the reference ranges (and in gray for LDH). The P values are as specified in the figure comparing the paired area under the curve of the mean of the outcome parameter for the N = 14 volunteers from 0 to 24 hours after the fresh and older transfusions.