The size of the community rather than its geographical location better defines the risk of iodine deficiency: Results of an extensive survey in Southern Italy

Aim: The objective of this study was to establish the status of iodine nutrition in Southern Italy. Material and methods: The survey was carried out on 11-14 yr old children attending primary school and living in urban and non urban areas of 8 regions of Southern Italy. Urinary iodine excretion (UIE) was measured in 23,103 urinary samples randomly collected. Results: Median UIE in the whole studied population was 74 μg/l [interquartile range (IR) 34-139 μg/l]. UIE was significantly higher in chief towns compared to non chief towns (81 μg/l, IR 39-145 μg/l vs 73 μg/l, IR 33-138 μg/l, p<0.0001) and in areas with >500 inhabitants per km2 (median 87 μg/l, IR 43-154 μg/l) compared to areas with 100-500 per km2 (median 66 μg/l, IR 29-126 μg/l, p<0.0001) and with <100 per km2 (median 61 μg/l, IR 25-121 μg/l, p<0.0001). Median UIE was significantly lower in inland mountainous/hilly areas (68 μg/l, IR 30-129 μg/l) compared to coastal mountainous/hilly areas (79 μg/l, IR 37-144 μg/l, p<0.0001) and lowland (79 μg/l, IR 37-146 μg/l, p<0.0001). According to a binary logistic regression model, population density was the only independent parameter significantly associated with UIE≥100 μg/l. Conclusion: The results of the present survey indicate that: 1) in Southern Italy mild to moderate iodine deficiency is still present; 2) median UIE in non urban areas is lower than in urban areas and is related to the size of the community rather than to its geographical location, being higher in a larger community. This may be due to better diversification of dietary habits and the easier availability of iodized salt and processed food through commercial facilities, more common in larger communities. Future monitoring surveys should take into account these observations.