2 SENSITIVE IMMUNOMETRIC ASSAYS FOR SERUM THYROID-STIMULATING HORMONEEVALUATED

This study was conducted to evaluate the analytical performance (funct ional sensitivity, reproducibility, parallelism, and accuracy) of two recent commercial kits marketed as third generation immunometric assay s for measuring serum thyroid stimulating hormone (TSH). One assay is automated; the other is manual. Accuracy by method comparisons was eva luated using 86 patient samples assayed by an established third genera tion immunometric assay as the comparative method. The new assays met the third generation criterion for functional sensitivity (CV less tha n or equal to 20 pet-cent at TSH less than or equal to 0.02 mIU/L), we re reproducible (CVs < 11 percent), and measured serum TSI-I in parall el with the calibrator curves. Linear regression analysis of the inter -method comparison data showed highly correlated (R > 0.95) results; h owever, the regression slopes were non-unity, indicating patient sampl e results were not transferable between methods. Clinical laboratories choosing a third generation TSH assay should validate tile performanc e characteristics of the selected method to ensure reliable results fo r patient care.