engleski

Impact of iodine deficiency/excess on thyroid morphology and function

Low iodine intake is known as a main etiologic factor of endemic goiter development. The aim of this study was to estimate the significance of morphological and functional thyroid changes caused by iodine deficiency or excess. The study was proospective, including 293 pts. (261 women, 32 men, mean age 44 ). Iodine in casual urine sample provides a reasonably good estimate of iodine intake. Iodine deficency ( <100 g/l )was found in 78% of pts. Iodine excess was found only in pts treated with amiodarone. T3/T4 ratio was significantly decreased in the group with excess iodine intake. Frequency of hypo and hyperthyroidism was similar in iodine excess/deficiency. Relation between estimates iodine intake and 131-I accumation in thyroid was quantified. Regression analyses revealed that exponential decreasing function was the best fit of measured points. All pts were submitted to ultrasound examinationin th e group with excess iodine autoimmune thyroiditis was found in 66, 6%. There was no significant difference in proportion of diffuse goiter and normally sized thyroid nodules in our groups. However enlarged thyroid with nodules was found in significantly higher proportion ( p< 0, 05 )in deficient (52%)than in normal iodine intake (36%). There were no such changes in the group with iodine excess. In 145 pts with thyroid nodules US guided FNAB revealed 34 tumors. The ratio of folicular tumors and papilary carcinomas was 1, 86 in the group with iodine deficiency and 1, 80 in the group with normal iodine values. Majority of our pts suffer from insufficient iodine supply connected with nodular goiter as a common finding. Autoimmune thyroiditis was the most frequent in the group iodine excess. Thyroid hormone profile was altered in a similar way in iodine deficiency as in iodine excess but T3/T4 ratio was significantly decreased in the group of pts with iodine excess.

Thyroid morphology; iodine deficiency; iodine excess

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