[Immunochemiluminometric assay (Automated Chemiluminescence System ACS: 180) for CEA]

We examined Automated Chemiluminescence System ACS: 180 for CEA assay, especially about confidence of the functional sensitivity. Serum CEA levels of normal subjects and patients were measured not only with ACS: 180 but also with immunoradiometric assay (CEA kit [Daiichi] II). Using ACS: 180 assay for CEA, intra-assay coefficients of variation (C.V.s) were 4.06% at 1.97 ng/ml, 1.62% at 17.3 ng/ml, and 2.28% at 81.3 ng/ml. Interassay C.V.s were 4.02% at 1.99 ng/ml, 1.21% at 16.5 ng/ml, and 3.44% at 79.4 ng/ml. The detection limit (functional sensitivity) of ACS: 180 assay for CEA was 0.4 ng/ml by the precision profile. The coefficient of correlation of 164 sera, which CEA values were among 0.4-100 ng/ml (working range of ACS: 180), between with ACS: 180 and with CEA kit [Daiichi] II was R = 0.942, y = 1.07 x +0.09 (p < 0.05). Seven (13.2%) normal subjects (n = 53) and 45 (34.1%) patients with malignant diseases (n = 132) had higher serum CEA levels than the cut off value (2.5 ng/ml). The sera of 82 malignant patients who had both pre- and post-operation sample were determined. Sixty-five patients of them were decrease after operation. These results of ACS: 180 resembled to that of CEA kit [Daiichi] II. We conclude that ACS: 180 for CEA assay was precise enough to measure below the cut off value, and had good performance of its speed (short incubation) and convenience.