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de Swart L, Hendriks JCM, van der Vorm LN, Cabantchik ZI, Evans PJ, Hod EA, Brittenham GM, Furman Y, Wojczyk B, Janssen MCH, Porter JB, Mattijssen VEJM, Biemond BJ, MacKenzie MA, Origa R, Galanello R, Hider RC, Swinkels DW. Second international round robin for the quantification of serum non-transferrin-bound iron and labile plasma iron in patients with iron-overload disorders. Haematologica 2015; 101:38-45. [PMID: 26385212 DOI: 10.3324/haematol.2015.133983] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 09/18/2015] [Indexed: 01/19/2023] Open
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.
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Affiliation(s)
- Louise de Swart
- Departments of Hematology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jan C M Hendriks
- Health Evidence, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Lisa N van der Vorm
- Department of Laboratory Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Z Ioav Cabantchik
- Department of Biochemical Chemistry, Hebrew University of Jerusalem, Israel
| | | | - Eldad A Hod
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY, USA
| | - Gary M Brittenham
- Department of Pediatrics, Columbia University Medical Center, New York, NY, USA
| | | | - Boguslaw Wojczyk
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY, USA
| | - Mirian C H Janssen
- Department of Internal Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - John B Porter
- Department of Haematology, University College London, UK
| | | | - Bart J Biemond
- Department of Hematology, Academic Medical Center, Amsterdam, The Netherlands
| | - Marius A MacKenzie
- Departments of Hematology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Raffaella Origa
- Department of Biomedical Science and Biotechnology, Regional Microcythemia Hospital, University of Cagliari, Italy
| | - Renzo Galanello
- Department of Biomedical Science and Biotechnology, Regional Microcythemia Hospital, University of Cagliari, Italy
| | - Robert C Hider
- Institute of Pharmaceutical Science, King's College London, UK
| | - Dorine W Swinkels
- Department of Laboratory Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
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