Performance characteristics of a new Immulite® 2000 system erythropoietin assay

Background: Serum erythropoietin (EPO) measurements are useful for diagnostic evaluations of anemia, polycythemia, and other erythroid disorders. Methods: We evaluated a new formulation of the chemiluminescent immunoassay for EPO on the Immulite 2000 analyzer (Siemens Healthcare Diagnostics) for limit of blank (LoB), imprecision, linearity, interference, comparison to another commercially available assay, reference interval, and cross-reactivity with 2 recombinant EPO preparations. Results: The LoB was 0.23 IU/l. Total imprecision ranged from 4.2 to 12.1%. The assay was linear from 0 to 678 IU/l. Hemoglobin caused negative interference at concentrations >17.4 g/l. Deming regression from the method comparison study gave a slope of 1.00 +/- 0.04, an intercept of 3.9 +/- 12.7, and a S-y/x of 44.9 (r=0.98). The non-parametric reference interval was 33 to 23.4 IU/l. Epoetin alfa at a 1:2000 dilution gave mean results of 541 IU/l and 650 IU/l for Immulite 2000 and Access 2, respectively. Darbopoetin alfa at a 1:2000 dilution gave mean results of 337 IU/l and 579 IU/l for the Immulite 2000 and Access 2, respectively, indicating the 2 assays have substantially different cross-reactivities with recombinant EPO preparations. Conclusions: The new Immulite 2000 EPO assay shows acceptable performance and is suitable for routine clinical use. (C) 2010 Elsevier B.V. All rights reserved.