The rate of iron loading varies considerably with the transfusion modality used. The loading rate with simple transfusion is higher when the target %HbS is lower (Kim et al12 ). Automated exchange can be adjusted to achieve minimal iron loading. Iron excretion as a function of dose has been calculated for DFO and DFX chelation therapy (Cohen et al11 ) so that appropriate doses to maintain iron balance can be shown. Larger doses are required to decrease SF or LIC.