[Comparison of two strategies for the early detection of congenital hypothyroidism].

OBJECTIVE

Compare two different strategies in newborn screening for congenital hypothyroidism, primary TSH in the umbilical cord blood (method 1) and primary T4 in blood collected from the heel in the 2nd day of life (method 2).

METHODS

We compared both strategies in 10,000 newborns, measuring TSH by a sensitive immunofluorimetric assay and T4 by a radioimmunoassay.

RESULTS

Both strategies detected all cases of hypothyroidism (4 cases, 1/2,500 newborns). The recalling index owing to insufficient amount of blood to perform the assays was zero in method 1 and 8.5% (850 newborns) in method 2. The recalling index for confirmation of the results was 0.06% (6 newborns) in method 1 and 2.25% (225 newborns) in method 2; when method 2 included supplementary TSH, the recalling index was reduced to 1.63% (163 newborns).

CONCLUSION

Our data indicate the technical superiority of the umbilical cord blood compared to heel and primary TSH compared to primary T4 in the neonatal thyroid screening for congenital hypothyroidism.