Thyroid autoimmunity is associated with higher urinary iodine concentrations in an iodine-deficient area of northwestern Greece

Northwestern Greece was identified in the 1960s for its high prevalence of endemic goiter and iodine deficiency. Although iodized salt has been commer cially available since then, a recent epidemiological survey of 3916 school -children found that low-grade goiter is still prevalent in endemic proport ions (21%). The aim of this study was to further assess the cause of goiter and the severity of iodine deficiency in children from this endemic area o f Greece. Of the 800 children with clinically detectable goiter, 97 childre n (60 girls and 37 boys, 8-15 years) were recruited for determination of ur inary iodine excretion, as well as assessment of thyroid volume and functio n and detection of antithyroid antibodies. The median urinary iodine concen tration was 8.4 mu g/dL, indicative of a mild iodine deficiency. Thyroid fu nction was normal in all but 11 children who had subclinical hypothyroidism . Sixteen children (16.5%), including all those with subclinical hypothyroi dism, were positive for antithyroid antibodies. Their median urinary iodine concentration (20.6 mu g/dL) was higher compared to children who were nega tive for antibodies (7.4 mu g/dL; p < 0.001). The mean thyroid volume by ul trasonography (12.2 +/- 4.1 mL) was above the upper limit of normal for thi s age group. Thyroid volume was inversely related to the urinary iodine con tent in the children with negative antithyroid antibodies. Iodine deficienc y is still prevalent in northwestern Greece although of mild severity and c onstitutes the primary cause of goiter among schoolchildren. However, it ap pears that autoimmune thyroiditis is emerging as a frequent cause of goiter in those children with sufficient iodine intake.