[Methodological study of different qualities of filter paper in the radioimmunological determination of thyrotropin in newborn infants].

In the screening of newborns for congenital hypothyroidism, filter paper cards act as sample carriers for capillary blood specimens, and for reference quantities of the measured hormones. Therefore, the quality of the filter paper is especially important and must be taken into account. Different types of filter paper and different guide marks on the paper surface for spotting blood specimens were investigated. The hormone distribution within the dried blood spot and the time necessary to extract the hormones were examined in relation to the sensitivity and yield of the test kit.