Multisite evaluation of a monoclonal IMMULITE erythropoietin immunoassay

• Erythropoietin (EPO) is useful in diagnosing anemias and polycythemias.
• A multisite evaluation of a monoclonal IMMULITE EPO assay was performed.
• Assay was comparable to Access 2 method using many relevant disease state samples.
• Reference intervals were established in healthy individuals with normal hematocrits.
• Assay had good reproducibility, sensitivity, and linearity over wide dynamic range.

BackgroundErythropoietin (EPO) measurements are useful in diagnosing anemias and polycythemias. We conducted a multisite evaluation of a monoclonal IMMULITE® EPO immunoassay.1Design and methodsThe IMMULITE EPO assay is a solid-phase enzyme-labeled chemiluminescent immunometric assay. Method comparison to the Beckman ACCESS 2 assay using clinically characterized samples and reproducibility studies were conducted at three external independent laboratories. Internal evaluation conducted at Siemens included comparison of IMMULITE® 2000 and IMMULITE® 1000 assays to the ACCESS 2 assay; imprecision; linearity; limit of blank (LoB), limit of detection (LoD), and functional sensitivity; potential interference and cross-reactants; and reference interval determination.ResultsExternal method comparison gave Deming regression of (IMMULITE 2000) = 0.96(ACCESS 2) + 2.57 IU/L, r = 0.98 (n = 217). Reproducibility ranged from 6.1% to 16.2%. Internal method comparisons gave Deming regressions of (IMMULITE 2000) = 1.09(ACCESS 2)− 3.51 IU/L, r = 0.98 and (IMMULITE 1000) = 0.95(ACCESS 2) + 0.52 IU/L, r = 0.95. Total imprecision ranged from 6.4% to 10.3% and linearity was confirmed from 3.5 to 562 IU/L. LoB, LoD, and functional sensitivity were 0.5, 1.0, and 1.5 IU/L, respectively. The assay was highly specific for EPO. Nonparametric reference interval was 4.3 to 29.0 IU/L (n = 170).ConclusionsThe monoclonal IMMULITE EPO assay showed acceptable performance for EPO measurement.