Assessment of iodine deficiency disorders after 15 years of universal salt iodization in Chongqing

Objective To assess the current status of iodine deficiency disorders in Chongqing following 15 years of universal salt iodization so as to provide scientific evidence.Methods Probability sampling method was used to select 30 counties in Chongqing.40 children aged 8 to 10 years from one school in each county were checked for thymus,salt and urinary iodine,daily salt intake using B-ultrasonograghy,direct drop method,Ce arsenic acid digestion and 3-day weighing method.Urinary iodine was also measured for pregnant and lactating women.Results A total of 1 322 students were surveyed with the total goiter rate of 5.52%.and there were 6.67% counties with the rate over 10%.The median salt iodine was 29.90 mg/kg.The coverage of iodized salt and the consumption rate of qualified iodized salt were 99.62%,and 96.67%,respectively.There were significant differences of consumption rate of qualified iodized salt among counties(χ2=53.47,P0.05).The amount of daily salt intake was 8.44 g per resident.The median urine iodine among children,pregnant and lactating women were 254.10 μg/L,223.85 μg/L and 219.60 μg/L which showed significant differences among counties in each population(Hchildren=121.27,Hpregnant woman=58.57,Hlactating woman=55.34,all P0.01).There were 9.68%,12.86% and 14.07% individuals in three groups whose urine iodine was lower than 100 μg/L,and 36.38%,32.59% and 31.82% individuals with urine iodine of above 300 μg/L.Conclusions In general,the total goiter rate,coverage rate of iodized salt,intaking rate of qualified iodized salt and urine iodine are all in the range of standard for eliminating iodine deficiency disorders in Chongqing. However,there are still shortage and overdose of iodine.