Statistical correlation of the erythrocytes' labile iron concentration with hemoglobin and total serum ferritin. (A) Erythrocyte labile iron was measured by the calcein methodology and the permeant Fe²⁺-specific chelator, BIP, as described in “Patients, materials, and methods.” Hemoglobins of patients with HbSS, HbSC, and HbSβ-thalassemia were measured by standard technique. The results were analyzed by linear regression. The p and P values are shown in the inserts. Dotted lines indicate the 95% confidence limits. (B) Correlation with the erythrocyte labile Fe²⁺ concentration with logarithm of total serum ferritin concentration of patients with hemoglobin SS, hemoglobin SC, and Sβ-thalassemia genotypes. The p and P values are shown in the inserts. Dotted lines indicate the 95% confidence limits.