Measurement of serum chorionic gonadotropin by a biotin-avidin labeled enzyme immunoassay.

A biotin-avidin enzyme immunoassay (EIA) for the measurement of human chorionic gonadotropin (hCG) in serum is described. This procedure involves the use of specific antibody immobilized on beads, biotin-labeled specific antibody, and enzyme-labeled avidin. Reproducible results were achieved within three hours for hCG in serum in the range of two mIU/ml to 150 mIU/ml. HCG levels as low as 0.4 mIU/ml can be measured. The biotin-avidin EIA and two commercially-available radioimmunoassay (RIA) kits were used to determine serum hCG levels on a group of patient samples. Good agreement was found between the biotin-avidin EIA and the RIA methods.