[Screening for neonatal hypothyroidism by measurement of both T4 and TSH in dried blood eluates (author's transl)].

Systematic screening for neonatal hypothyroidism has been undertaken since January 1977 in Southern France by the measurement of both T4 and TSH in dried blood eluates. 76,432 measurements were performed in 3 years and 22 cases of hypothyroidism were detected. There were several advantages of this method; detection of all forms of thyroid disease, immediate diagnosis of primary hypothyroidism with T4 < -2 S.D. and TSH > 80 microU/ml, decrease in the number of false positive results, detection of some false negative values with normal T4 but high TSH values. In Southern France the frequency of thyroid abnormalities is 1/34,000 births. The causes of these abnormalities in 22 cases was as follows: Absent thyroid (10), ectopic thyroid (11) and one thyroid in the normal position. In all cases TSH levels were above 80 microU/ml but in six cases with ectopic thyroids the T4 levels were between -1 and -2 S.D. These cases would not have been detected with T4 measurements alone.