Association Between Thyroid Nodules and Volume and Metabolic Syndrome in an Iodine-Adequate Area: A Large Community-Based Population Study

Background: Given its high incidence, thyroid nodule (TN) warrants public attention. Thyroid volume (TV) has also been associated with multiple factors, such as iodine deficiency and supply and body mass index. It is well known that metabolic syndrome (MetS) comprises many metabolic disturbances, with insulin resistance being its major component. Materials and Methods: The aim of this study was to investigate the relationship between TN and TV and MetS and its components in an iodine-adequate area in Asia. All participants were asked to complete a questionnaire. After excluding 938 individuals based on the exclusion criteria, we reviewed data from 927 of 1865 participants. Adopting MetS diagnostic criteria, we found 437 subjects to be MetS positive [MetS(+)] and 490 subjects to be MetS negative [MetS(-)], respectively. Multivariate linear regression was used to assess the relationship between TNs and MetS. Moreover, univariate binary logistic regression analyses were used to calculate odds ratios (ORs), and 95% confidence intervals (CIs) were used to estimate the associations between different variables and TNs. Results: A total of 232 females and 205 males were MetS(+), as diagnosed using the International Diabetes Federation criteria. However, there were 330 females and 160 males in the group of MetS(-) individuals. The prevalence of TNs was 38.29% in the MetS(+) group and 17.79% in the MetS(-) group. After adjusting for systolic blood pressure, diastolic blood pressure, and gender, only high-density lipoprotein, waist circumference (WC), and age were related to TNs (OR = 0.45, 95% CI 0.27-0.75, P = 0.0023; OR = 1.04, 95% CI 1.02-1.06, P = 0.0036). The TV of all participants was 13.98 (11.24, 17.01) mL; 13.26 (10.62, 16.17) mL for females and 14.96 (11.83, 18.01) mL for males. It was found that only WC was related to TV, after controlling for sex and age (P = 0.02). Conclusions: The morbidity among TN patients in the MetS(+) group was higher than that among the MetS(-) group. High-density lipoprotein cholesterol emerged as a protective factor, and WC was a risk factor for TN. Moreover, TV was related to MetS, and WC was an independent risk factor for TV.