Relationship between the Prevalence of Thyroid Nodules and Metabolic Syndrome in the Iodine-Adequate Area of Hangzhou, China: A Cross-Sectional and Cohort Study

Abstract

Objective. The association between thyroid nodule (TN) prevalence and metabolic syndrome (MetS) has only rarely been examined in iodine-adequate areas and needs further clarification. We investigated correlations between MetS and TN prevalence in the iodine-adequate area of Hangzhou, China. Material and Method. A cross-sectional study that screened and recruited individuals for cohort research 3 years later. The 13522 subjects (8926 men, 4596 women) were screened in 2009 for all MetS components, thyroid ultrasound (US), and thyroid function. Cohort research recruited 1610 subjects who were screened in both 2009 and 2012, of whom 1061 underwent follow-up research. Results. The prevalence of TN was higher in the MetS (+) group than in the MetS (-) group (χ (2) = 69.63, P < 0.001) and higher in women than in men (χ (2) = 11.65, P = 0.001). Waist circumference (WC) was positively related to the prevalence of TN (OR = 1.022, P < 0.001). Individuals with greater WC in 2009 were more likely to suffer from TN in 2012 (RR = 1.434, P = 0.024). Elevated triglyceride level was a risk factor for developing new TN (RR = 1.001, P = 0.035). Conclusion. Both greater WC and elevated triglycerides are risk factors for new TN in this iodine-adequate area in China.

Figure 1

Prevalence of thyroid nodules. (a) The prevalence of thyroid nodules for women was significantly higher than for men in the 40 to 49 age range, 50 to 59 age range, and the age above 70 (χ ² = 8.904, P = 0.003; χ ² = 29.044, P < 0.001; χ ² = 4.631, P = 0.031, respectively). The prevalence of thyroid nodules increased along with increasing age (trend χ ² test: χ ² = 515.22 for men, P < 0.001; χ ² = 921.56 for women, P < 0.001). (b) The prevalence of thyroid nodule in the MetS (+) group was higher than in the MetS (−) group for both sexes together (41.71% (1157/2774) versus 33.23% (3572/10748), χ ² = 69.63, P < 0.001) and for men and women separately (female: 48.15% (260/540) versus 35.43% (1437/4056), χ ² = 33.10, P < 0.001; male: 40.15% (897/2234) versus 31.90% (2135/6692), χ ² = 50.80, P < 0.001).