Iodine Nutrition and the Prevalence Status of Thyroid Nodules in the Population: a Cross-sectional Survey in Heilongjiang Province, China

The aim of this study was to determine the iodine nutritional status and the epidemiological characteristics of thyroid nodules (TNs) in the adult population of Heilongjiang Province. From December 2017 to December 2018, a total of 3661 adults aged 20-70 years were selected through probability proportional to size (PPS) sampling for a cross-sectional survey. During the field epidemiological investigation, each participant received a questionnaire survey and thyroid ultrasonography examination. The iodine concentrations in casual urine specimens and household edible salt were measured. The household coverage of iodized salt was 86.56%. The median urinary iodine concentration (MUIC) in the adult population in Heilongjiang Province was 161.57 μg/L (25th-75th percentile: 100.35-245.15 μg/L). The prevalence of TNs was 36.88%, and the prevalence in females was significantly higher than that in males (41.25% vs 32.50%, χ² = 11.841, P < 0.01). The prevalence of TNs increased with age (χ²_trend = 49.80, P < 0.001). The prevalence of multiple TNs increased with age (χ²_trend = 48.709, P < 0.001). There was no significant difference in the MUIC between healthy control group and those with TNs (Z = - 1.386, P = 0.166). The female, age (40-49 age group, 50-59 age group, 60-70 age group), BMI (obesity, overweight), history of hypertension, history of diabetes, and smoking history were all independent risk factors that affected the occurrence of TNs. The iodine nutritional status of the adult population in Heilongjiang Province was adequate. The prevalence of TNs was higher in middle-aged and elderly women, so these individuals should be the focus of the prevention and treatment of thyroid nodule disease.