[Development of a radioimmunoassay for thyrotropin (TSH) in dried blood spots together with a comparison of 7 commercial kits (author's transl)].

The blood-spot thyrotropin RIA for detection of congenital hypothyroidism has been established as a screening programme. This article describes the problems in hand, namely optimisation of the method and a comparison of the performance in 7 commercial kits on the West German market. The following factors have been investigated: a. Shelf-life of standards and samples b. Effect of filter paper quality and weight c. Size of paper disc d. Blood sampling time e. Time of removal of paper disc f. Effect on the results of washing the precipitate. The commercial kits at present on the market differ widely in method and price. Apart from this, there was no agreement between the results obtained, and the difference between the standard concentration given by the firm compared with the reference standard MRC 68/38 varied from 22--185%. Methodological guidelines and quality control measures, both internal and external, are suggested.