Second international round robin for the quantification of serum non-transferrin-bound iron and labile plasma iron in patients with iron-overload disorders

Louise de Swart, Jan C.M. Hendriks, Lisa N. van der Vorm, Z. Ioav Cabantchik, Patricia J. Evans, Eldad A. Hod, Gary M. Brittenham, Yael Furman, Boguslaw Wojczyk, Mirian C.H. Janssen, John B. Porter, Vera E.J.M. Mattijssen, Bart J. Biemond, Marius A. Mackenzie, Raffaella Origa, Renzo Galanello, Robert C. Hider, Dorine W. Swinkels*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

76 Scopus citations

Abstract

Non-transferrin-bound iron and its labile (redox active) plasma iron component are thought to be potentially toxic forms of iron originally identified in the serum of patients with iron overload. We compared ten worldwide leading assays (6 for non-transferrinbound iron and 4 for labile plasma iron) as part of an international interlaboratory study. Serum samples from 60 patients with four different iron-overload disorders in various treatment phases were coded and sent in duplicate for analysis to five different laboratories worldwide. Some laboratories provided multiple assays. Overall, highest assay levels were observed for patients with untreated hereditary hemochromatosis and β-thalassemia intermedia, patients with transfusion-dependent myelodysplastic syndromes and patients with transfusion-dependent and chelated β-thalassemia major. Absolute levels differed considerably between assays and were lower for labile plasma iron than for non-transferrin-bound iron. Four assays also reported negative values. Assays were reproducible with high between-sample and low withinsample variation. Assays correlated and correlations were highest within the group of non-transferrin-bound iron assays and within that of labile plasma iron assays. Increased transferrin saturation, but not ferritin, was a good indicator of the presence of forms of circulating nontransferrin- bound iron. The possibility of using non-transferrin-bound iron and labile plasma iron measures as clinical indicators of overt iron overload and/or of treatment efficacy would largely depend on the rigorous validation and standardization of assays.

Original languageEnglish
Pages (from-to)38-45
Number of pages8
JournalHaematologica
Volume101
Issue number1
DOIs
StatePublished - 2016

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©2016 Ferrata Storti Foundation.

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