Results of in vivo RBC survival study. (A-C) Three PNH patients (UPNs 1, 2, and 3 in Table 1) with suboptimal response to eculizumab studied by 51Cr RBC labeling. Excess counts on spleen (continuous line) and liver (dashed line) are plotted after correction for background, radioactive decay, and blood radioactivity (ie, heart counts), in function of time. Hatched and filled gray areas represent normal range for liver and spleen excess counts, respectively. Increased entrapment of RBCs in spleen and liver was observed in all the 3 PNH patients. (D) A representative example of a patient with a hyporegenerative (nonhemolytic) anemia, showing no liver or spleen excess count (RBC half-life, 35 days). (E) A representative example of a patient with hemolytic anemia due to extravascular hemolysis, showing liver and especially spleen excess counts (RBC half-life, 8 days).
