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

ABSTRACT

BACKGROUND AND OBJECTIVES: 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. METHODS AND STUDY DESIGN: 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. RESULTS: 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. CONCLUSION: 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.