Cobas Core CA 19-9 II EIA: new CA 19-9 enzyme immunoassay with high correlation to radioimmunoassays

Especially in patients with pancreatic carcinoma (1-5) (89%) the high molecular weight mucin CA 19-9 (MG 210 kD) shows a high specificity (98.5%) and sensitivity (up to 82%) (6-7). The mayor problem in the field of CA 19-9 diagnostics is the lack of satisfying comparability between CA 19-9 test kits: external proficiency studies (8) indicate a discrepancy between enzymatic and isotopic tests regarding their correlation. The Cobas Core CA 19-9 EIA II contributes to the standardisation of the CA 19-9 kits and allows the switching over from CA 19-9 IRMA's to EIA's. The test can be performed on the random access immunochemistry analyzer Cobas Core with a total assay time of 75 minutes by using 20 microliters of serum or plasma specimens. The analytical sensitivity was determined to be > 0.3 IU/ml. The 2 recalibrators cover a measuring range from 0 to 400 IU/ml. A high-dose-hook effect was not observed up to a concentration of 400,000 IU/ml. Interferences from the sample caused by heterophilic antibodies are reduced to a minimum. Precisions for intra-assay and inter-assay ranged below 5% and 6% respectively. In summary, the Cobas Core CA 19-9 II EIA exhibits a significant improvement regarding the correlation to CA 19-9 radioimmunometric methods (CIS, Centocor).