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Haematologica. 2016 Jan;101(1):38-45. doi: 10.3324/haematol.2015.133983. Epub 2015 Sep 18.

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

Author information

1
Departments of Hematology, Radboud University Medical Center, Nijmegen, The Netherlands.
2
Health Evidence, Radboud University Medical Center, Nijmegen, The Netherlands.
3
Department of Laboratory Medicine, Radboud University Medical Center, Nijmegen, The Netherlands.
4
Department of Biochemical Chemistry, Hebrew University of Jerusalem, Israel.
5
Department of Haematology, University College London, UK.
6
Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY, USA.
7
Department of Pediatrics, Columbia University Medical Center, New York, NY, USA.
8
Aferrix Ltd., Tel-Aviv, Israel.
9
Department of Internal Medicine, Radboud University Medical Center, Nijmegen, The Netherlands.
10
Department of Hematology, Rijnstate Hospital, Arnhem, The Netherlands.
11
Department of Hematology, Academic Medical Center, Amsterdam, The Netherlands.
12
Department of Biomedical Science and Biotechnology, Regional Microcythemia Hospital, University of Cagliari, Italy.
13
Institute of Pharmaceutical Science, King's College London, UK.
14
Department of Laboratory Medicine, Radboud University Medical Center, Nijmegen, The Netherlands dorine.swinkels@radboudumc.nl.

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-transferrin-bound iron and 4 for labile plasma iron) as part of an international inter-laboratory 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 within-sample 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 non-transferrin-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.

PMID:
26385212
PMCID:
PMC4697890
DOI:
10.3324/haematol.2015.133983
[Indexed for MEDLINE]
Free PMC Article

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