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 mu Ul/ml whole blood. TSH values >20 mu Ul/ml were excluded from further analysis of the data. The frequency distribution analysis showed that the median neonatal TSH level was 2 mu Ul/ml and the mode (28% of newborns) corresponded to neonatal TSH values <1 mu Ul/ml, TSH levels above 5 mu Ul/ml were observed in 14.4% children and the 97% cut off was 11 mu Ul/ml. When examined in relation to the areas of newborn origin, the individual 97% cut off values varied from 8 to 14 mu Ul/ml. Accordingly, the frequency of TSH levels above the 97% cut off value calculated for the entire newborn series (>11 mu Ul/ml) ranged from 2.1% to 4.6%, A significant correlation was found between the frequency of neonatal TSH levels >11 mu Ul/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, (C) 1997, Editrice Kurtis.