An evaluation of kits for measuring thyrotropin in newborns

Several commercial radioimmunoassay kits are now marketed specifically for determination of thyrotropin (TSH) from whole-blood specimens collected on filter paper in neonatal screening programs. We have compared five kits in use in such screening programs in the United States. The reagent kits from Becton Dickinson, Neometrics, and Nuclear Medical Systems gave similar satisfactory results. That from Pharmacia was somewhat more difficult to use and gave greater coefficients of variation. Diagnostic Products' kit appeared to perform satisfactorily, but the analytical values obtained were significantly low, which may suggest erroneous calibrator values within the kit.