Abstract
In Finland thyroid screening was started in October 1979 and stepwise expanded to cover the whole country by mid-1980. Other metabolic defects worth neonatal screening are unknown in our country. Hence we can use the earliest possible screening, and cord serum samples are mailed to this laboratory from the whole country. Until October 1980 all infants with TSH >45mU/1 were placed on thyroxin substitution immediately after drawing a second blood sample and clinical examination. If TSH was normal in the second sample the therapy was discontinued. Among 33500 infants screened 12 sure or propable cases of hypothyroidism were detected (0.036% or 1/2790). 0.21% were false positives. To decrease this figure we then elevated the (primary alarm) limit to 60 mU/1 and started determining T4 from the samples with TSH level between 45 and 60 mU/1, giving alarm in cases with T4 <120 nmol/1 (secondary alarm limit). Of 30510 infants so screened by April 1981 8 were hypothyroid by the primary limit and one by the secondary limit (0.029% or 1/3390). 0.06% were false positives. We are aware of one "false negative" case; it was due to maintenance of euthyroidism by foeto-foetal transfusion. Our median age at start of therapy is 5 days (TSH limit) or 8 days (T4 limit).
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Virtanen, M., Axelson, E., Huttunen, J. et al. Screening for congenital hypothyroidism in Finland. Pediatr Res 15, 1555 (1981). https://doi.org/10.1203/00006450-198112000-00123
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DOI: https://doi.org/10.1203/00006450-198112000-00123