Bleomycin-detectable Iron Assay for Non-Transferrin-bound Iron in Hematologic Malignancies

• Published in: Clinical chemistry (Baltimore, Md.) Md.), 2002-02, Vol.48 (2), p.307-314
• Main Authors: von Bonsdorff, Leni, Lindeberg, Enni, Sahlstedt, Leila, Lehto, Jari, Parkkinen, Jaakko
• Format: Article
• Language: English
• Subjects: Antineoplastic Agents, Alkylating - therapeutic use; Biological and medical sciences; Bleomycin; Combined Modality Therapy; Cyclophosphamide - therapeutic use; Electrophoresis, Polyacrylamide Gel; Hematologic Neoplasms - blood; Hematologic Neoplasms - therapy; Hematology; Hematopoietic Stem Cell Transplantation; Hemolysis; Humans; Investigative techniques, diagnostic techniques (general aspects); Iron - blood; Iron - metabolism; Iron Chelating Agents; Medical sciences; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; Reproducibility of Results; Sensitivity and Specificity; Transferrin - metabolism; Whole-Body Irradiation
• ISSN: 0009-9147; 1530-8561
• DOI: 10.1093/clinchem/48.2.307

A microwell modification of the bleomycin assay for determining non-transferrin-bound iron (NTBI) was evaluated and compared with a chelation method. The bleomycin assay reagent and sample volumes were halved, and measurements were done in microwell plates. Samples from patients treated for hematologic malignancies were studied. The chelation method was based on mobilization of NTBI with a chelator and measurement of the ultrafiltered iron-chelator complex. NTBI results were also compared with transferrin saturation and the distribution of transferrin iron forms by urea-polyacrylamide gel electrophoresis. The bleomycin assay intraassay imprecision (CV) was 7.7% and 8.2% and the interassay imprecision was 18% and 9.8% for a low (0.2 micromol/L) and a high (1.5 micromol/L) contrtrol, respectively. Hemolysis increased measured NTBI. A detection limit of 0.1 micromol/L was established based on the interference of nonvisible hemolysis and on accuracy studies. In patient samples, NTBI exceeded the detection limits only when transferrin saturation was >80%. Compared with the chelation method, the bleomycin assay gave clearly lower NTBI concentrations. The chelation method also gave positive results at 80%, suggesting high specificity. Bleomycin-detectable iron constitutes only a portion of the NTBI measured by the chelation method.