Assessment of Sustainable Elimination Criteria for Iodine Deficiency Disorders Recommended by International Organizations

Lijun Fan, Fangang Meng, Qihao Sun, Yuqian Zhai, Peng Liu, Lijun Fan, Fangang Meng, Qihao Sun, Yuqian Zhai, Peng Liu

Abstract

Enormous efforts have been made to evaluate the worldwide prevention and control of iodine deficiency disorders (IDDs). This study evaluated China's achievements in IDD prevention and control against WHO criteria for sustainable elimination of IDD. The study sample consisted of 556,390 school-aged children and 271,935 pregnant women enrolled in the 2018 China National IDD Surveillance. As a result, at the national level, median urine iodine concentration (MUIC) was 206.1 and 163.5 μg/l in children and in pregnant women, respectively. The proportion of households consuming adequate iodized salt (PHCAIS) was 90.2%. The prevalence rates of goiter in children and thyroid disease in pregnant women were 2.0 and 0.8%, respectively. MUIC showed significant non-linear increasing trends with increasing PHCAIS in both children and pregnant women. The prevalence of thyroid disease in pregnant women had a sharp decreasing trend with increasing PHCAIS. Of note, the prevalence of goiter in children and thyroid disease in pregnant women against MUIC both presented as significant U-shaped curves, with the lowest prevalence at 100-300 μg/l of MUIC in children and 150-250 μg/l in pregnant women. PHCAIS, MUIC, and the programmatic indicators at the national level were all above their cut-offs proposed in the 2007 Criteria. Evaluation by adding the prevalence of goiter (<5%) yielded the different results at the county level. Sustainable elimination of IDD has been achieved nationally. 2018 Chinese surveillance data support the expansion of global cut-offs for optimal iodine status in school-age children from 100-199 to 100-299 μg/l as recommended by others and the lower limit of MUIC (150 μg/l) in pregnant women also seems justified. Inclusion of goiter prevalence <5% in our analysis reduced the number of municipalities and counties which had achieved sustainable elimination of IDD.

Keywords: goiter prevalence; iodine deficiency disorders; iodized salt; sustainable elimination; urine iodine concentration.

Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Copyright © 2022 Fan, Meng, Sun, Zhai and Liu.

Figures

Figure 1
Figure 1
The influence of iodized salt on thyroid disease and iodine nutrition. MUIC, median urine iodine concentration; PHCAIS, proportion of households consuming adequately iodized salt; TD, thyroid disease. (A,B) children and (C,D) pregnant women. p <0.0001 for trend in all 3 age groups in (B).
Figure 2
Figure 2
The relationships of MUIC with goiter in children (A) and TD in pregnant women (B). MUIC, median urine iodine concentration; TD, thyroid disease. (A)R2 = 0.7763 and (B)R2 = 0.3059.

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