Association between Urinary Iodine Concentration and Thyroid Nodules in Adults: A Cross-Sectional Study in China.

Jiajun Zhao,Li Yu,Bingyin Shi,Shu Wang,Juan Zheng,Hanyu Wang,Jiaoyue Zhang,Nanwei Tong,Lulu Chen,Xiang Hu,Yunxia Tu,Ali Abbara,Chao Liu,Lixin Shi,Zhongyan Shan,Weiping Teng,Jianping Weng,Hui Sun,Xiaolan Lian

doi:10.1155/2020/4138657

Abstract

Background Associations between iodine intake and thyroid nodules (TNs) were not consistent. We aimed to illustrate the relationship between urinary iodine concentration (UIC) and TNs. Methods A total of 12,698 participants were enrolled in analysis. All of the participants filled out questionnaires and underwent physical examinations, laboratory tests, and thyroid ultrasonography. UIC, serum thyrotropin (TSH), thyroid peroxidase antibodies (TPOAb), and thyroglobulin antibodies (TgAb) were measured in the central laboratory. Results The prevalence of TNs was 16.00%, and the median UIC was 206.1 μg/L. TNs and UIC were negatively related when UIC was less than 527 μg/L (adjusted OR = 0.87; 95% CI, 0.80, 0.94), and the relationship between UIC and TNs was not statistically significant when UIC was greater than 527 μg/L (adjusted OR = 1.25; 95% CI, 0.98, 1.60). In women, UIC was negatively associated with risk for TNs (adjusted OR 0.95; 95% CI, 0.91, 0.99). Conclusion The relationship between TNs and UIC differed between men and women. The risk of TNs decreased with the elevation of UIC in men when UIC was lower than 527 μg/L, while UIC and the presence of TNs were negatively correlated in women. In the future, cohort studies or other studies that can explain causality must be conducted to explore the relationship between iodine status and TNs.

Highlights

The detection of thyroid nodules has become increasingly common with the expanded use of ultrasonographic examinations
In 2002, the central government revised the national mandate for salt iodization, and the median urinary iodine concentration (UIC) decreased to 246 μg/L in 2005 [11]
We observed a negative association between UIC and thyroid nodules when UIC was lower than 527 μg/L, and using LRT, we achieved p of 0.018, indicating that a nonlinear relationship existed between UIC and thyroid nodules

Summary

Introduction

The detection of thyroid nodules has become increasingly common with the expanded use of ultrasonographic examinations. Thyroid nodules cause a number of clinical symptoms, such as vocal hoarseness, compressive symptoms, and dysphagia [2,3,4,5], which can harm health. They are associated with many factors, including age, sex, iodine nutrition status, thyroid autoimmune antibodies, and metabolic syndrome [6,7,8], but of these, iodine nutrition status is one of the most closely related and important factors. UIC was negatively associated with risk for TNs (adjusted OR 0.95; 95% CI, 0.91, 0.99).

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Discussion

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