Association of serum total bilirubin with traditional and novel cardiovascular risk factors in apparently healthy subjects

Abstract

Background. Bilirubin is considered as one of the strongest endogenous antioxidants. Recent studies suggest that high total bilirubin levels are associated with lower cardiovascular disease (CVD) risk. The aim of this study was to evaluate a the relationship between serum total bilirubin and traditional as well as new risk factors for CVD in apparently healthy subjects.

Materials and methods. Study included 60 non-smoking, non-obese individuals (30 females, 30 males) with normal fasting glucose, aged 25–40 years. In all subjects basic anthropometric indicators (weight, WHR, BMI), blood pressure and laboratory tests: serum total bilirubin (Bil-T), lipid profile, CRP, plasma glucose, apolipoproteins AI and B and 25-hydroxyvitamin D were performed. Subjects were divided into two groups of relative CVD risk, specified by total bilirubin levels: low-risk (≥ 13.7 μmol/L) and high-risk (< 13.7 μmol/L).

Results. Total bilirubin ranged 6.16–32.15 μmol/L. In the study group 58% of subjects had Bil-T values above 13.7 μmol/L. Higher values occurred more frequently in men (70%) and in subjects aged 30–40 years (71%). Statistically significant relationship between Bil-T, and traditional and new risk factors for CVD was found. Bil-T correlated negatively with non-HDL-C, LDL-C, systolic blood pressure as well as with apoB: apoAI ratio, apolipoprotein B, TC:HDL-C and TC. A weak positive correlation was found between serum Bil-T and HDL-C. Additionally, negative correlations with CRP and positive with 25-hydroxyvitamin D were observed in women. In subjects with low CVD risk, the prevalence of low LDL-C concentration (< 2.59 mmol/L) was nearly three-fold higher compared with high-risk groups. Furthermore, in low-risk group the prevalence of serum CRP < 1 mg/L and HDL-C levels > 1.55 mmol/L was 2-fold and 3-fold higher, respectively, and higher incidence of low apoB:apoAI values (<0.6) was observed.

Conclusions. Serum total bilirubin may play an important role in reducing the risk of CVD, therefore its assay seems to be valuable for more accurate assessment of cardiovascular risk in young, non-obese, non-diabetic individuals.