Serum retinol-binding protein 4 is associated with the presence and severity of coronary artery disease in patients with subclinical hypothyroidism

Subclinical hypothyroidism (SCH) plays a crucial role in the development and progression of coronary heart disease (CAD). Retinol-binding protein 4 (RBP4) is an adipokine correlated with cardiovascular diseases. Recent studies found that RBP4 levels are increased in patients with SCH. However, the relationship of RBP4 with CAD in SCH patients remains unclear. A total of 199 SCH patients (148 with CAD and 51 without CAD) and 102 healthy controls were enrolled in this study. Serum RBP4 was increased in SCH patients than controls. Moreover, serum RBP4 was higher in SCH patients with CAD. Although there was no significant difference of metabolic parameters between SCH patients with and without CAD, serum RBP4 was positively correlated with body mass index, total cholesterol, and low-density lipoprotein cholesterol, as well as thyroid stimulating hormone. Multivariable logistic regression analyses revealed elevated RBP4 was correlated with increased risk for CAD in SCH patients. Serum RBP4 levels were also increased as the number of stenosed vessels increased. Furthermore, increased RBP4 was positively correlated with the severity of CAD quantified by the Gensini score. Our findings demonstrate that serum RBP4 is associated with the presence and severity of CAD in patients with SCH.