Association of Subclinical Hypothyroidism with Cardiovascular Risk Factors and Coronary Artery Calcium Score

ABSTRACT

BACKGROUND: Few studies have investigated the association between subclinical hypothyroidism (SCH) and coronary artery calcification (CAC). This study investigated this association in patients who visited a health promotion center.METHODS: This study included patients who visited the Health Promotion Center at a University Hospital between January 2014 and December 2015. Serum thyroid stimulating hormone (TSH) level, free thyroxine level, and the CAC score (CACS) were measured in all patients. Patients were classified into euthyroid and SCH groups. An independent t-test and chi-squared test were performed to analyze the general characteristics. Patients were further classified into three groups based on serum TSH levels (serum TSH level < 4.0, 4.0–10, and >10 µIU/mL), and the one-way analysis of variance test was performed to assess the clinical differences among three groups. Partial correlation coefficients were calculated to assess the correlation between serum TSH levels and cardiovascular risk factors. Patients with CACS=0 were classified into the non-calcification group, and those with CACS >0 were classified into the calcification group. The odds ratios of SCH to CAC were analyzed using logistic regression analysis.RESULTS: Serum TSH levels were significantly associated with body mass index, waist circumference, high-density lipoprotein cholesterol, and triglyceride levels. The risk of obesity, diabetes, and high triglyceride levels (>150 mg/dL) was significantly higher in the SCH group. Moreover, the SCH group with TSH levels >10 µIU/mL showed a significant risk of CAC (odds ratio, 3.18; 95% confidence interval, 1.10–9.21).CONCLUSION: SCH with TSH levels >10 µIU/mL is independently associated with the CACS.