Association between cardiometabolic index and primary hypothyroidism: A cross-sectional study based the NHANES...

The Cardiometabolic Index (CMI) is emerging as a novel marker for assessing visceral obesity and dyslipidemia. This study aims to investigate the relationship between CMI and primary hypothyroidism among US adults. This cross-sectional study was conducted among adults with complete records of CMI and thyroid function information from the National Health and Nutrition Examination Survey (NHANES) 2007-2012. The calculation formula for CMI is Triglycerides (TG)/High-density lipoprotein cholesterol (HDL-C) × WHtR (WHtR = waist circumference/height). Weighted linear regression models and multivariate logistic regression models were employed to investigate the association between CMI and serum thyroid-stimulating hormone (TSH) level/primary hypothyroidism, respectively; additionally, restricted cubic spline (RCS) analysis was used to verify the nonlinear relationship. Subgroup analyses were performed to explore potential effect modifiers. 3304 participants, aged 20 years and older, were included from NHANES across 3 survey cycles. In this study, 6.69% of the participants were diagnosed with primary hypothyroidism. A higher CMI correlated consistently with increased serum TSH levels (β: 2.47; 95% confidence interval [CI]: 2.38-2.57) and primary hypothyroidism (odds ratio [OR]: 8.70; 95% CI: 4.93-15.37). In the fully corrected model, for each unit increase in CMI, the serum TSH levels increased by 0.70 mIU/L. Subgroup analyses showed that the association of CMI with primary hypothyroidism was stably present in all subgroups. Interaction effects were observed for gender and body mass index subgroup (P for interaction: < .05). RCS regression highlighted a significant positive nonlinear association between CMI and TSH level/primary hypothyroidism (P for non-linearity < .001). Our results indicated a significant positive association between CMI levels and serum TSH level and primary hypothyroidism risk among US adults.