Incidence of congenital hypothyroidism in the Autonomous Province of Bolzano: benefit of increased iodine intake.

PURPOSE: Although a nation-wide salt iodization program on voluntary basis was implemented in 2005, many areas in our country are still characterized by mild iodine deficiency. Differently from the rest of Italy, an efficient program of iodine prophylaxis was implemented in 1981 in the Autonomous Province of Bolzano. The aim of this study was to investigate whether an adequate iodine intake in the population may affect the incidence of permanent congenital hypothyroidism (CH). METHODS: The incidence trends of permanent CH between 1987 and 2006 in Bolzano Province and in the rest of Italy were estimated. RESULTS: Over the years, the CH incidence has remained steadily lower in Bolzano than in the rest of the country. CONCLUSIONS: Primary prevention of permanent CH may be possible by assuring an adequate nutritional iodine intake in the population. However, the time needed to observe a decrease in the incidence of CH is about a decade under conditions of iodine sufficiency.

Thyroid function of subjects with goitre and cretinism in an endemic goitre area of rural China after use of iodized salt.

Endemic goitre and cretinism are still a public health problem in China. An epidemiological survey showed that about 5% of the inhabitants in Daxin village, Henan province, had goitre or cretinism after an iodized salt prevention programme had been carried out for two decades. The main food for the inhabitants of this area has an iodine content less than 30 nmol/kg and the water for cooking and drinking has an iodine concentration between 7-12 nmol/l. We studied thyroid function in subjects of this village. There were 42 with grade 0 goitre (males 29, females 13), 42 grade I (males 23, females 19), 27 grade II (males 9, females 18), 31 grade III (males 14, females 17) and 34 cretinism patients (males 30, females 4) diagnosed and classified according to WHO criteria. Serum T4, free T4, T3, free T3, T3 uptake, TSH and thyroglobulin were measured in these subjects. The patients with goitre or cretinism had significantly decreased serum free T4 and increased serum T3 and free T3 levels compared with those of controls. Thyroid size was positively correlated with age and serum thyroglobulin concentrations. Serum thyroglobulin was significantly increased even in the grade 0 goitre subjects. The percentages of subjects with serum free T4 less than 12 nmol/l, T3 greater than 2.5 nmol/l, free T3 greater than 5.2 pmol/l, TSH greater than 3.5 mU/l, T3/T4 ratio greater than 0.03 and free T3/free T4 ratio greater than 0.36 were significantly higher among goitre and cretinism patients than among controls. The data suggest that there is partial compensation for a marginal deficiency of iodine in the inhabitants of this village.