Effect of therapeutic concentrations of chelators on LPI in sera of thalassemia major patients. Iron chelators were added at the indicated concentrations to sera from 2 thalassemia major patients (A and B) undergoing therapy with orally administered DFP (75 mg/kg/d) and showing substantial levels of LPI after more than 10-hour washout period (since last intake of DFP). The bars denote: the mean LPI value of 0.4 ± 0.2 μM of 10 normal individuals (normal = no iron overload); LPI values of serum samples from thalassemia patient A and B to which had been added the concentrations of chelators indicated under each bar. The respective initial LPI values for A and B were 1.75 and 4.85 μM, representing 2 different classes of LPI levels that are attained in the plasma following more than 10-hour drug washout. The chelators were allowed to act on sera for 1 hour at 37°C before LPI was analyzed, as described elsewhere.³⁶  The broken line represents the empirical background level of the LPI assay. Deferasirox: ▪; deferrioxamine: ▨; deferiprone: □.