Hypothyroidism in children with filter paper TSH of 30 to 50 microU/ml at initial screening. Implication of the TSH cut-off point for recalling of infants at risk.

In a systematic screening of newborns in France during the period from 1979 to 1983, 959 infants with hypothyroidism were detected. In 16 cases of confirmed hypothyroidism the initial filter paper TSH (FP-TSH) was between 30 and 50 microU/ml. These cases emphasize the necessity of keeping a "security zone" for FP-TSH value between 30 and 50 microU/ml and of recalling these patients for a second test filter paper TSH.