A study on association of serum bilirubin, c-reactive Protein and lipid profile in coronary artery disease

Background: Coronary artery disease (CAD) remains one of the leading causes of death worldwide, primarily due to atherosclerosis, a chronic inflammatory condition affecting the vascular endothelium. Among the key mechanisms contributing to CAD progression are lipid abnormalities, oxidative stress, and systemic inflammation. Biomarkers such as C-reactive protein (CRP) and bilirubin have gained attention for their potential roles in risk assessment. While CRP is a known pro-inflammatory marker associated with acute coronary syndromes, bilirubin, traditionally seen as a waste product, is now recognized for its antioxidant and anti-inflammatory properties. The interplay between lipid profile, CRP, and bilirubin may provide a better understanding of CAD risk and prognosis. Objective: To evaluate the relationship of serum bilirubin and C-reactive protein levels with coronary artery disease, and assess their association with lipid profile parameters in CAD patients compared to non-coronary controls. Methods: A cross-sectional prospective study was conducted over 18 months (July 2023 to December 2024) at Al-Ameen Medical College Hospital, Vijayapura, Karnataka. The study enrolled patients aged 26 to 75 years admitted to the medicine department with confirmed diagnoses of CAD, ischemic heart disease, or myocardial infarction based on electrocardiogram, echocardiography, angiographic findings, and cardiac history. Age and sex-matched controls without CAD were also included. Patients with liver, renal, inflammatory, autoimmune, or infectious diseases were excluded. Serum CRP was measured using a CRP-Latex slide agglutination test and categorized into low, average, and high-risk groups. Serum bilirubin and lipid profiles were measured using standard laboratory methods. Results: The majority of CAD patients exhibited elevated CRP levels, particularly in the high-risk range (>3 mg/L), whereas controls showed lower levels. Serum bilirubin levels were significantly lower in CAD patients compared to controls, supporting its proposed protective role. Lipid analysis revealed elevated total cholesterol, triglycerides, and LDL cholesterol in CAD patients, while HDL levels were reduced. A significant inverse correlation was observed between bilirubin levels and CRP, indicating the potential of bilirubin to counteract inflammation. Patients with both high CRP and low bilirubin demonstrated greater severity of CAD. Lipid abnormalities, especially raised LDL and low HDL, showed strong associations with CRP levels and adverse cardiovascular risk stratification. Conclusion: Low bilirubin and high C-reactive protein levels are independently associated with an increased risk of coronary artery disease. Their combination, along with deranged lipid parameters, significantly contributes to cardiovascular risk. These findings support the integration of bilirubin and CRP in risk prediction models for CAD. Early detection and targeted intervention based on inflammatory and oxidative biomarkers may improve outcomes in at-risk populations