Thyroid volume and urinary iodine excretion in the schoolchild population of a Northwestern Italian sub-Alp metropolitan area

Iodine deficiency is recognised as a major preventable public-health worldwide problem. The aim of this study is to assess local reference values for thyroid volume, and give a snapshot of the epidemiology of goiter and iodine nutritional status of the Turin schoolchild population. Sonographic thyroid volume and median urinary iodine excretion were obtained in 1067 schoolchildren aged 11-15 yr resident in Turin for more than 5 yr to assess both goiter prevalence and iodine intake. All the subjects were asked to fill in a questionnaire about their life habits. Anamnestic and anthropometric data, thyroid volume by both bimanual palpation and ultrasonography were assessed, and spot urinary iodine samples were collected. The results show that the median urinary iodine concentration is 113.1 microg/l and the prevalence of goiter <5%, indicating this area as iodine-sufficient. Nevertheless, 40.5% of the schoolchild population has urinary iodine levels lower than the cut-off level recommended as iodine-sufficiency. Interestingly, the high relative prevalence of ultrasound features of autoimmune thyroid disease suggests autoimmune-thyroiditis as a frequent thyroid disease in Turin schoolchildren. As no active programs of salt, milk or water iodisation have ever been carried out, a silent iodine prophylaxis has probably occurred in the city. Despite a sufficient median urinary iodine excretion, a focused program of iodine prophylaxis should be developed due to the presence of a large rate of iodine-deficient population.