Iodine status and its association with prevalence of thyroid diseases in adults from Jiangxi Province, China

Abstract

Background: Iodine is an essential element for biosynthesis of thyroid-stimulating hormone (TSH). Both excessive and de ciency of iodine are major risk factor for thyroid diseases, including thyroid dysfunction, thyroid nodules, and thyroid autoimmunity (TAI). This study aimed to elucidate the relationship between iodine status and incidence of thyroid diseases through a national cross-sectional epidemiological survey (TIDE) in Jiangxi province (China).Methods: A population-based, cross-sectional study enrolled a total of 2636 Chinese local inhabitants who aged over 18 years from April to August in 2015. Physical examination was performed and biochemical indices, urinary iodine concentration (UIC), and TSH levels were measured and documented for each subject. The Chi-square test, nonparametric test, and 4 multiple logistic regression models adjusted for other risk factors were applied to analysis, and Spearman correlation coe cients were used to investigate the relationship between iodine intake level and the incidence of thyroid diseases.Results: The median UIC was 176.4 μg/L, and a signi cant difference was found in median UIC between males(182.5 μg/L) and females (169.2 μg/L) (P =0.03). Among these participants, 14.4%, 44.5%, 26.1%, and 15.0% had de ciency, adequate, more than adequate, and excessive iodine concentrations, respectively. The incidence rates of hyperthyroidism, subclinical hyperthyroidism, hypothyroidism, subclinical hypothyroidism, thyroid nodules, and TAI were 0.91%, 0.57%, 0.34% and 7.89%, 9.45%, and 12.74%, respectively. Signi cant differences were found in iodine status, waist circumstance, systolic blood pressure (SBP), diastolic blood pressure (DBP), total cholesterol (TC), TSH, thyroid nodules, and TAI between males and females (P <0.05). Compared with those with adequate UIC, subjects with excessive UIC had higher incidence rates of thyroid dysfunction (odds ratio (OR)=1.74, 95% con dence interval (CI):1.40-2.54) and thyroid nodules (OR=3.33, 95%CI 1.32-8.42). In addition, subjects with de cient and excessive UIC were at a higher risk of TAI compared with those with adequate UIC (OR=1.68, 95%CI: 1.19-2.60; OR=1.52, 95%CI: 1.04-2.96, respectively). UIC was positively correlated with the incidence rates of thyroid nodules (r=-0.44, P<0.01) and TAI (r=-0.055, P <0.01). On the contrary, UIC was negatively correlated with the risk of thyroid dysfunction (r=-0.24, P >0.05).Conclusion: Adult inhabitants from Jiangxi province in the TIDE study were in the adequate iodine status.The incidence rates of of thyroid dysfunction, thyroid nodules, and TAI were higher in females. Excessive iodine status was noted as a risk factor for thyroid dysfunction and thyroid nodules. In addition, both iodine de ciency and excessive iodine were risk factors for TAI.

Associations of Combined Exposure to Metabolic and Inflammatory Indicators with Thyroid Nodules in Adults: A Nested Case-Control Study

“…For example, China launched a mandatory universal salt iodization program in 1996, which has been efective in controlling thyroid-related diseases [12]. However, recent studies also suggested that excessive iodine intake may increase the risk of thyroid nodules [12][13][14]. Tus, there is an urgent need to identify several additional modifable risk factors, especially key factors, in adults.…”