Simplified direct radioimmunoassay method for measuring carcinoembryonic antigen

The radioimmunoassay for carcinoembryonic antigen as usually carried out is an involved, time-consuming procedure complicated by the use of a dialysis step to remove perchloric acid from an extract of the sample. A simplified direct assay for the antigen in serum or plasma is reported here. It is evaluated in comparison with our earlier method which was done using perchloric acid extraction of the samples. The results of the simplified method compare favorably with those of the indirect method.