Date Published: March 22, 2017
Publisher: Public Library of Science
Author(s): Linlin Xiu, Gansheng Zhong, Xueman Ma, Stephen L. Clarke.
To evaluate whether urinary iodine concentration (UIC) can predict goiter among school-age children, and to assess the association between UIC and goiter prevalence.
We searched the MEDLINE, EMBASE, Cochrane Library (Cochrane Database of Systematic Reviews), Web of Science, CNKI, VIP, and Wan Fang databases for relevant reports in both English and Chinese up to August 25, 2016. The mean differences (MD) and 95% confidence intervals (CI) were calculated for the UIC and goiter prevalence assessments. Pooled odds ratios and 95% CIs were used to compare the prevalences of goiter in the different UIC groups.
We identified 11 case-control studies, and found that children with goiter had lower UIC values, compared to children without goiter (MD: –1.82, 95% CI: –3.24, –0.40, p < 0.05). An increased risk of goiter was associated with UIC values of < 20 μg/L or > 200 μg/L.
The results of our meta-analysis suggest that lower UIC values were associated with an increased risk of goiter, and that iodine deficiency may lead to an increased risk of goiter. Furthermore, we observed U-shaped relationships between UIC and the prevalence of goiter, which suggests that both severe iodine deficiency and excessive iodine intake may lead to increased risks of goiter.
Goiter remains an important public health concern, especially in developing countries [1–3]. During recent decades, goiter was mainly considered the result of inadequate iodine intake, although excessive iodine intake can also cause goiter, especially in areas with high iodine levels, such as coastal areas, areas with high iodine levels in the drinking water, and areas with poor iodine monitoring [4–6]. Thus, both inadequate and excessive iodine intakes are considered risk factors for goiter [7–10].
Iodine is an essential micronutrient that is required to synthesize thyroid hormones, and universal salt iodization is considered an appropriate method for iodine fortification in developed countries . However, adverse effects have been recognized and careful monitoring is essential, as excessive iodine intake is associated with an increased risk of goiter and other iodine-related thyroid diseases. Thus, it is important to understand the association between iodine status and goiter prevalence after the implementation of the universal salt iodization. As UIC is highly sensitive to recent changes in iodine intake, UIC may be a reliable indicator for assessing, monitoring, and evaluating iodine status [28, 29]. For example, UIC might be a useful indicator of the effect of universal salt iodization and may help predict the occurrence of goiter.