Changes in serum T4, T3 and TSH concentrations in newborns and infants with congenital goiter from the Mazovia region.

Thyroid function was investigated in a group of 61 newborns with congenital goiter before starting the therapy with thyroid hormones. The group included 19 girls and 42 boys, of which 27 were of age not exceeding one week (group I), 19 were between the first and the second week (group II), and 15 were between the second week and the third month of life (group III). The concentrations of the thyroid hormones were determined by radioimmunoassay. The values obtained have been compared with the local reference range obtained for the newborns of the Mazovia region. The values remaining outside the reference range were found in 47.5% of the newborns studied. The elevated values of TSH were observed mainly in group I newborns (12 from 27); among group II newborns there was only one with the elevated values, and none among the newborns of group III. thyroxine (T4) values were lowered in 14 among 27 newborns of group I, and in 2 among 19 newborns of group II; all T4 values were normal in group III. The percentage of the elevated values of triiodothyronine (T3) was higher in older newborns (group III). The elevated level of T3 accompanied by the lowered level of T4 with the normal or moderately elevated level of TSH is characteristic for the adaptation to the deficiency of iodine. There is preferential secretion of T3 aimed at maintaining euthyreosis. The elevated levels of T3 found in 30% of newborns with untreated goiter suggest an intrauterine deficit of iodine as a cause of the goiter appearance.(ABSTRACT TRUNCATED AT 250 WORDS)