[Screening for neonatal hypothyroidism by estimation of T4 (author's transl)]

Over a 21 month period simultaneous screening for phenylketonuria and hypothyroidism by estimation of T4 was undertaken in 139,730 newborns. TSH was estimated in those with lowest T4 values. 22 cases of primary hypothyroidism, 26 with TBG deficiency and 8 with transient hypothyroidism were detected. There were a relatively high number of false positive results which should in theory be close to 5% (because the cut off fevel for T4 was 1.6 S.D. below the mean). This was reduced at 3.3% on the second specimen using a screening protocol in which T4, TSH and TBG were all estimated. Clinical analysis of the results suggests that TSH is probably the method of choice for screening for hypothyroidism.