Analytical and clinical evaluation of an electrochemiluminescence immunoassay for the determination of CA 125

The CA 125 II assay on the Elecsys(R) 2010 analyzer was evaluated in an int ernational multicenter trial. Imprecision studies yielded within-run CVs of 0.8-3.3% and between-day CVs of 2.4-10.9%; CVs for total imprecision in th e manufacturer's laboratory were 2.4-7.8%, The linear range of the assay ex tended to at least 4500 kilounits/L (three decades), Interference from trig lycerides (10.3 mmol/L), bilirubin (850 mu mol/L), hemoglobin (1.1 mmol/L), anticoagulants (plasma), and several widely used drugs was undetectable. M ethod comparisons with five other CA 125 II assays showed good correlation but differences in standardization. A 95th percentile cutoff value of 35 ki lounits/L, was calculated from values measured in 593 apparently healthy (p re- and postmenopausal) women. In 95% of patients with benign gynecological diseases CA 125 was less than or equal to 190 kilounits/L; 63% of patients with newly diagnosed ovarian carcinoma had values >190 kilounits/L. A comp arison of CA 125 values obtained with the Elecsys test and with other commo n CA 125 tests in monitored patients being treated for ovarian cancer showe d identical patterns. In conclusion, the Elecsys CA 125 II assay is linear over a broad range, yields precise and accurate results, is free from inter ferences, and compares well with other assays.