Serial plasma haptoglobin and nontransferrin-bound iron and labile iron levels. (A) Plasma haptoglobin levels were lower in 42 (closed circle, solid line) compared with 7 (open circle, dashed line) day-old blood at 10 hours (P = .02), 24 hours (P = .03), and 48 hours (P = .03). Data presented as mean ± SE. (B) Nontransferrin-bound iron (top plot) and labile plasma iron (bottom plot) were significantly increased with 42- (right plot) but not 7-day-old (left plot) stored blood at 13 hours (during transfusion) compared with 4 hours (just before transfusion; both P = .03). After the transfusions were finished at 24 hours with 7- and 42-day-old blood, the nontransferrin-bound and labile iron were not significantly elevated (both P = NS). Note: One data value at 4 hours of 42-day-old blood of nontransferrin-bound iron was excluded because of an very high value measured before transfusion (shown in figure), whereas the corresponding labile plasma iron level and CFH level for this animal was not elevated which would be inconsistent with our understanding of the biology. If we include this value, the nontransferrin-bound iron at 13 hours compared with 4 hours with 42-day-old blood is not significantly different (P = .20). Data are presented as individual values (open circle), mean (dark dash), median (solid line), 75th and 25th percentile (bounds of gray box) and 95th percentile (error bars).