Abstract

Introduction: Correct interpretation of ultrasonographic measurement of thyroid volume in goiter surveys depends on the availability of valid reference criteria from iodine sufficient populations. There is a lack of consensus of opinions on universal reference values for thyroid volume. Our objective was to describe thyroid volume measured by ultrasonography in Tehranian schoolchildren who had been living in an iodine sufficient area their entire life. Materials and Methods: This cross-sectional study was performed on 464 schoolchildren, aged 7-15 yr in Tehran, fifteen years after distribution of iodized salt. Data were collected on age, sex, weight, and thyroid size was ascertained by palpation and ultrasonography. Results: The prevalence of goiter was 2.3% by palpation. All goitrous subjects had grade 1 goiter thyroid volumes determined by ultrasonography were comparable in boys and girls of all ages. The best predictors of thyroid volume were age, weight, and body surface area. The median thyroid volumes of Tehranian schoolchildren in this study were lower in all age groups compared with our previous 2001 study and updated provisional WHO/ICCIDD reference values. Conclusion: Tehranian schoolchildren currently living in an iodine sufficient area, where they have spent their entire lives, have smaller thyroid glands than recommended international references. Existing values for universal thyroid volume reference ranges should be re-considered.