MEASUREMENT OF URINARY IODINE EXCRETION TO REVEAL IODINE EXCESS IN NEONATAL TRANSIENT HYPOTHYROIDISM

This study was undertaken to confirm the importance of iodine excess i n neonatal transient hypothyroidism. In 30 transient hypothyroid newbo rns at screening we measured urinary iodine excretion and TSH. They we re divided into two groups: group A consisted of 21 newborns who had b een exposed to iodine; group B of 9 non-exposed newborns. The two grou ps were significantly different only for median urinary iodine excreti on (p=0.001), In 61.5% of newborns of group A, iodine exposure caused iodine excess (urinary iodine excretion higher than 185 mu g/l); this correlated with a higher prevalence of prematurity and a lower mean ge stational age. Clinical records should reveal iodine exposure, but onl y urinary iodine excretion shows iodine excess. We suggest that evalua tion at birth of urinary iodine excretion in every newborn with high T SH could help in predicting a good prognosis, since hypothyroidism due to the Wolff-Chaikoff effect is always spontaneously reversible, even if treatment may be suggested.