The statistical analysis of neonatal TSH results from congenital hypothyroidism screening programs provides a useful tool for the characterization of moderate iodine deficiency regions

TSH data from the congenital hypothyroidism screening program were analyzed in a mild to moderate iodine deficiency region. Neonatal TSH levels were measured at day 4–5 of life in 22,384 infants (99% coverage; 51.1% males, 48.9% females). The cut off TSH value for recall was established at 20 µUI/ml whole blood. TSH values >20 µUI/ml were excluded from further analysis of the data. The frequency distribution analysis showed that the median neonatal TSH level was 2 µUI/ml and the mode (28% of newborns) corresponded to neonatal TSH values 11 µUI/ml) ranged from 2.1% to 4.6%. A significant correlation was found between the frequency of neonatal TSH levels >11 µUI/ml and both goiter prevalence (r 2=0.88; p=0.0019) and median urinary iodine excretion (r 2=0.86; p=0.0077) observed in those areas for which epidemiological data were available (n=7). The results indicate that neonatal TSH data from the congenital hypothyroidism screening programs can be used for monitoring mild to moderate iodine deficiency regions.