RESUMO
Different nutritional and environmental factors are responsible for the pathogenesis of goiter, but iodine deficiency is the most important factor. However, little is known about the natural course of benign thyroid nodules in euthyroid patients over time. Few studies have used ultrasonographic evaluation to address this issue, especially in iodine-deficient areas. In this study, we present the long-term follow-up of benign thyroid nodules in a iodine-deficient area. Cross-sectional study at a tertiary referral center. This study included 62 randomly selected patients with benign euthyroid nodule. Thyroid volume and nodules were measured with sonography. Iodine intake was estimated by patient diet history and by measuring iodine excretion in spot urine samples. Patients were followed one year. Patients were divided into three groups according to level of urine iodine excretion: Group 1: <50 micro g/L [severe iodine deficiency group], Group 2: 50-100 micro g/L [mild iodine deficiency group], Group 3: >100 micro g/L [iodine sufficient group]. The presence of additional disease [hypertension, diabetes mellitus, coronary heart disease, chronic renal failure and a history of any medication for chronic disorder] and smoking rates were significantly higher in first group compared to the second and third group. Among groups, no significant difference was observed in either right or left thyroid lobe volume after one year. A clinically significant increase in nodule volume was observed in the first group, while there was a significant decrease in the second and third group. In this study, iodine deficiency was associated with an increase in thyroid nodule volumes. Smoking rates were higher in iodine deficient groups. It is thought that smoking impairs iodine intake or absorption consistent with a previous report