Fetuin-A and kidney function in persons with coronary artery disease - Data from the heart and soul study

Abstract

Background. Fetuin-A is a serum protein that inhibits ectopic vascular calcification and is present in lower concentrations in end-stage renal disease than in healthy controls. Whether fetuin-A concentrations are also lower in the setting of mild-to-moderate chronic kidney disease (CKD) is unknown. Methods. We evaluated the associations of several parameters of kidney function including measured 24h urinary creatinine clearance (CrCl), estimated glomerular filtration rate (GFR) by the Mayo Clinic quadratic GFR equation (qGFR), serum cystatin-C concentrations, and urinary albumin-to-creatinine ratio with serum fetuin-A concentrations in 970 outpatients with coronary artery disease. We used general linear models to determine the adjusted mean fetuin-A concentrations within each kidney function category. Results. The mean age of the study sample was 67 years, 82% were male, 71% had hypertension and 26% had diabetes mellitus. In adjusted analysis, we observed no significant differences in mean fetuin-A concentrations across groups defined by CrCl, qGFR, or albumin-to-creatinine ratio groups. For example, adjusted mean fetuin-A concentrations were 0.66g/l in participants with CrCl > 90, 60-90 and 45-60ml/min/1.73m2, and 0.65g/l in participants with CrCl < 45ml/min/1.73m2. Higher serum cystatin-C (indicating worse kidney function) was associated with higher adjusted mean serum fetuin-A concentrations (lowest quartile 0.62g/l, highest quartile 0.68g/l; P for trend <0.001). Conclusions. Among ambulatory patients with coronary artery disease, there is no evidence that mild-to-moderate CKD is associated with lower concentrations of serum fetuin-A compared with persons with normal renal function. The mechanisms explaining the association between CKD and vascular calcification remain elusive. © 2006 Oxford University Press.