Association of thyroid nodules with adiposity: a community-based cross-sectional study in China

BACKGROUND: The association between thyroid nodules and adiposity remains controversial. We performed a cross-sectional, community-based study to examine whether thyroid nodules are associated with overweight and obesity, as defined with body mass index (BMI) and waist circumference. METHODS: The study included 1482 subjects (≥20 years of age; residing in Nanjing, China) receiving questionnaire interview, anthropometric measurements, laboratory tests and thyroid ultrasonography in 2009–2010. Overweight and obesity were defined as BMI ≥24 and ≥28 kg/m(2), respectively. Central obesity was defined as waist circumference at ≥90 cm in men and ≥80 cm in women. A sensitivity analysis was conducted using the American Diabetes Association (ADA) criteria for overweight and obesity (BMI ≥ 23 and ≥25 kg/m(2)). RESULTS: Thyroid nodules were identified in 12.6% of the subjects. A greater proportion of the subjects with thyroid nodules had a BMI at ≥24 kg/m(2) (51.9% vs. 40.5% in those without thyroid nodules, P = 0.003) and central obesity (43.3% vs. 24.2%, P < 0.001). After adjustment for other confounders, central obesity was still associated with significantly elevated risk of thyroid nodules (OR 1.62, 95%CI 1.14–2.28), whereas obesity/overweight based on BMI was not in both the main analysis and sensitivity analysis with the alternative criteria. In the subgroup analysis, BMI ≥24 kg/m(2) (OR 1.61, 95%CI 1.01–2.54), as well as BMI ≥25 kg/m(2) (OR 1.95, 95%CI 1.14–3.34), was significantly associated with higher risk of thyroid nodules among women. Using the ADA criteria, overweight and obesity were associated with thyroid nodules (OR 5.59, 95%CI 1.39–22.51 and 5.15, 95%CI 1.30–20.37) in thyroid-stimulating hormone (TSH) > 4.2 mIU/L subgroup. Central obesity correlated with higher risk of thyroid nodules regardless of age (< 50 years: OR 1.87, 95%CI 1.05–3.32: ≥50 years: OR 1.54, 95%CI 1.00–2.37) and in the following subgroups: men (OR 1.91, 95%CI 1.14–3.20), TSH > 4.2 mIU/L (OR 3.05, 95%CI 1.01–9.22), and urine iodine ≥200 µg/L (OR 1.79, 95%CI 1.14–2.81). CONCLUSION: Waist circumference is superior to BMI for assessing risk of thyroid nodules in Chinese subjects. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12902-018-0232-8) contains supplementary material, which is available to authorized users.