| Abstract: | Assays for human choriogonadotropin (HCG) and thyroid stimulating hormone (TSH) have typically been performed using radioisotopic procedures. Two newer, nonradioisotopic approaches, enzyme immunoassay (EIA) and fluorometric enzyme immunoassay (FEI), were evaluated for the determination of HCG and TSH. Two TSH EIA assays (Abbott, Hybritech) and one FEI assay (Dade) were compared with each other and an immunoradiometric (IRMA) assay. The FEI assay performed better than the EIA assays with a sensitivity of 0.3 microIU/ml, within-run closing volumes (CVs) of less than 4.5%, and a carryover of 0.7%. All of the assays correlated well with each other and the IRMA assay. Three HCG EIA assays (Abbott, Hybritech, Roche) and one FEI assay (Dade) were evaluated. Again, the FEI assay performed better than the EIA assays with a sensitivity of 1.3 mIU/ml, within-run CVs of 4.0% or less, and a carryover of 1.7%. The new generation of nonradioisotopic assays offers performance comparable to radioisotopic assays coupled with various degrees of automation. A clinical laboratory may not only take advantage of these methods but can choose an assay system that is well suited to its particular requirements. |
