Yao Ning, Zhou Chunbei, Xie Jun, Li Xinshu, Zhou Qianru, Chen Jing, Zhou Shuang
Chongqing Center for Disease Control and Prevention, Chongqing, People's Republic of China.
Endocr Connect. 2020 May;9(5):379-386. doi: 10.1530/EC-19-0568.
The remarkable success of iodine deficiency disorders (IDD) elimination in China has been achieved through a mandatory universal salt iodization (USI) program. The study aims to estimate the relationship between urinary iodine concentration (UIC) and iodine content in edible salt to assess the current iodine nutritional status of school aged children.
A total of 5565 students from 26 of 39 districts/counties in Chongqing participated in the study, UIC and iodine content in table salt were measured. Thyroid volumes of 3311 students were examined by ultrasound and goiter prevalence was calculated.
The overall median UIC of students was 222 μg/L (IQR: 150-313 μg/L). Median UIC was significantly different among groups with non-iodized salt (iodine content <5 mg/kg), inadequately iodized salt (between 5 and 21 mg/kg), adequately iodized (between 21 and 39 mg/kg) and excessively iodized (>39 mg/kg) salt (P < 0.01). The total goiter rate was 1.9% (60/3111) and 6.0% (186/3111) according to Chinese national and WHO reference values, respectively. Thyroid volume and goiter prevalence were not different within the three iodine nutritional status groups (insufficient, adequate and excessive, P > 0.05).
The efficient implementation of current USI program is able to reduce the goiter prevalence in Chongqing as a low incidence of goiter in school aged children is observed in this study. The widened UIC range of 100-299 μg/L indicating sufficient iodine intake is considered safe with a slim chance of causing goiter or thyroid dysfunction. Further researches were needed to evaluate the applicability of WHO reference in goiter diagnose in Chongqing or identifying more accurate criteria of normal thyroid volume of local students in the future.
中国通过强制实施全民食盐加碘（USI）计划，在消除碘缺乏病（IDD）方面取得了显著成功。本研究旨在评估尿碘浓度（UIC）与食用盐碘含量之间的关系，以评估学龄儿童当前的碘营养状况。
重庆39个区县中的26个区县的5565名学生参与了本研究，测量了UIC和食盐中的碘含量。通过超声检查了3311名学生的甲状腺体积，并计算了甲状腺肿患病率。
学生的总体UIC中位数为222μg/L（四分位间距：150 - 313μg/L）。在未加碘盐（碘含量<5mg/kg）、碘含量不足的盐（5至21mg/kg之间）、碘含量充足的盐（21至39mg/kg之间）和碘含量过量的盐（>39mg/kg）组中，UIC中位数有显著差异（P<0.01）。根据中国国家标准和世界卫生组织参考值，甲状腺肿总患病率分别为1.9%（60/3111）和6.0%（186/3111）。在三种碘营养状况组（不足、充足和过量，P>0.05）中，甲状腺体积和甲状腺肿患病率没有差异。
本研究观察到学龄儿童甲状腺肿发病率较低，当前USI计划的有效实施能够降低重庆的甲状腺肿患病率。UIC范围拓宽至100 - 299μg/L表明碘摄入充足，被认为是安全的，导致甲状腺肿或甲状腺功能障碍的可能性很小。未来需要进一步研究评估世界卫生组织参考值在重庆甲状腺肿诊断中的适用性，或确定当地学生正常甲状腺体积的更准确标准。
