Goitre and urinary iodine in coastal and inland areas with low and high iodized salt coverage in Zhejiang province, China.

Abstract

WHO recommended that iodized salt are more than 90% of households in USI programs, which may not be suitable for all regions, especially in coastal areas. This study intended to find out levels of iodine nutrition and give advice from the USI programs for areas with different iodized salt coverage. Coastal and inland areas were selected according to geographical regions in Zhejiang Province, China. The water iodine concentration (spectrophotometer analysis), salt iodine concentration (the colorimetric titration method), salt intake, urinary iodine concentration (spectrophotometer analysis), and thyroid volume examination (ultrasonography), as well as questionnaire, were measured in the two areas. Mean Urinary Iodine concentration (MUIs) of children in coastal areas was 149 μg/L, which was significantly lower than that in inland areas (191 μg/L). MUIs of pregnant women in coastal and inland areas were111 and 138 μg/L, respectively. Pregnant women who consumed iodine-containing supplements had higher MUIs (207 μg/L) than those did not (134 μg/L) in inland areas. Prevalence of goitre in children reached 7.0% and 6.6% in coastal and inland areas, respectively. The lowest prevalence of goitre was reached when the urinary iodine concentration was approximately 120-160 μg/L in coastal areas. Iodine levels of coastal and inland areas were in the adequate range. Advice from the USI program should be specialized for different areas to appropriately reduce the salt iodine concentrations in inland areas and to determine an appropriate proportion of households using iodized salt in coastal areas. Moreover, iodine supplement intake during pregnancy should officially be recommended.