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LPI-labile plasma iron in iron overload

https://doi.org/10.1016/j.beha.2004.10.003Get rights and content

Labile plasma iron (LPI) represents a component of non-transferrin-bound iron (NTBI) that is both redox-active and chelatable, capable of permeating into organs and inducing tissue iron overload. It appears in various types of hemosiderosis (transfusional and non-transfusional) and in other iron-overload conditions. Sustained levels of LPI could over time compromise organ (e.g. heart) function and patient survival. With the advent of methods for measuring LPI in the clinical setting, it has become possible to assess the implications of LPI in the management of iron overload based on regimens of iron chelation. As LPI is detected primarily in patients with transfusional iron overload and other forms of hemosiderosis, we review here regimens of iron chelation with deferrioxamine and deferiprone (separately or combined) in terms of their efficacy in minimizing daily exposure to LPI in thalassemia major and thalassemia intermedia patients.

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Why another assay for assessing iron overload?

Despite the success of daily DFO treatment in maintaining thalassemia major patients in negative iron balance over more than three decades, a significant number of patients have apparently developed serious and often fatal heart conditions.25, 26 In many cases these conditions could be attributed to iron accumulation in the heart rather than the liver due to their low correlations with liver iron or circulating ferritin.9, 10, 11, 12, 13, 14, 15, 16, 27, 28, 29 The proposed view is that the

LPI Levels in thalassemia

A new high-throughput technology (FeROS, Aferrix Ltd) was recently devised for assessing LPI in the clinical setting and has already been applied to more than 5000 serum samples, including patients with thalassemia (major and intermedia)22, 23, 34, hemochromatosis22, 33, diabetes35, dysmetabolic hepatosiderosis33, and myelodysplasmic syndrome.36 The assay is based on the capacity of LPI to generate reactive oxygen radicals when prompted with ascorbate in a manner blockable by specific iron

Summary

LPI values obtained following an extended drug washout period (basal LPI levels) provide a means for evaluating the efficacy of treatment in maintaining the individual at low levels of exposure to labile plasma iron.

LPI values vary among iron-overloaded patients in relation to the regimen of chelation and time of blood withdrawal. Although the basal LPI levels decline relatively faster than other iron-related parameters, they correlate linearly with serum ferritin levels as well as with

Acknowledgements

This work was supported in part by The European Community 5th Framework QLRT-2001-00444 (nutrient iron toxicity) and by Apopharma Inc, Ont., Canada.

References (36)

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