Changes of the spectrum on thyroid disease after the ten-year implementation of universal salt iodization in Guangxi Zhuang Autonomous Region

Abstract

To reveal the relationship between iodine nutrition and the change of spectrum on thyroid diseases through comparing the different iodine environments pre- and post- the universal salt iodization(USI)campaign. To compare the urinary iodine concentration between 1000 normal people and 5998 patients with thyroid disease who had undergone surgical operations, from 4 major cities, including iodine deficient and rich areas of Guangxi Zhuang Autonomous Region. After USI was put into practice, the urinary iodine concentration of patients with thyroid appeared higher than those of normal people(324.3 µg/L vs. 238.5 µg/L, P < 0.05). The urinary iodine concentrations of nodular goiter,Graves disease, toxic nodular goiter, thyroid papillary carcinoma and Hashimoto's thyroiditis were higher than those before the USI was taken(263.8 µg/L vs. 69.75 µg/L, 289.7 µg/L vs. 228.3 µg/L, 346.8 µg/L vs. 268.4 µg/L, 350.3 µg/L vs. 316.2 µg/L and 378.5 µg/L vs. 305.8 µg/L). The proportions of toxic nodular goiter, thyroid papillary carcinoma and Hashimoto's thyroiditis appeared as 7.59% vs. 4.80%, 5.85% vs. 4.02% and 3.88% vs. 2.46%, all higher than those before the implementation of USI, except the nodular goiter which showed a reduction (63.56% vs. 69.75%). The spectrum of thyroid diseases appeared an obvious change in Guangxi within the last 10-year implementation of USI. However, the excessive intake of iodine might serve as a risk factor for toxic nodular goiter, thyroid papillary carcinoma and Hashimoto's thyroiditis.