[Simultaneous thyroxin determination in thyrotropin (TSH) screening for congenital hypothyroidism (author's transl)]

A dried-blood screening test for demonstration of congenital hypothyroidism was developed using materials of a commercially available radioimmunoassay for estimation of thyroxin (T4) in serum. The method is characterised by simple performance and satisfactory precision (coefficient of variation 7.8-12.4%). Performance of the test parallel to single determination of thyrotropin (TSH) instead of the usual TSH double determination is considered. Diagnostic advantages of both methods can thus be combined. Screening is not burdened by additional cost. However, an increase of the number of follow-up investigations may be expected.