Serum osteoprotegerin as a screening tool for coronary artery calcification score in diabetic pre-dialysis patients

Although cardiovascular disease is a principal cause of death in patients with chronic kidney disease (CKD), it is often asymptomatic in diabetic patients. The coronary artery calcification score (CACS) measured by multidetector computed tomography (MDCT) is useful for screening ischemic heart disease in the general population. We investigated which clinical parameters predict high CACS in predialysis diabetic nephropathy (DN). Participants were 85 patients with DN. Nobody had any history of coronary angioplasty or coronary bypass surgery. We measured blood counts, blood chemistry, bone alkaline phosphatase, intact-PTH, interleukin-6, osteoprotegerin (OPG), hemoglobin A1c, 25-hydroxyvitamin D (25(OH)D) and fetuin-A. CACS and bone mineral density (BMD) were measured by a single 16-slice MDCT and DEXA, respectively. The median value of CACS equaled 256 Agatston units (range 0-4494 units). Stepwise increase in CACS with CKD stage progression was observed (p<0.01 for trend). Simple regression analyses showed that Log (CACS+1) was positively correlated with age, systolic blood pressure, phosphorus and OPG. In addition, it was negatively correlated with nutritional parameters, such as body mass index, albumin, total-cholesterol and 25(OH)D. Fetuin-A and BMD had no impact on CACS. Multiple regression analyses showed that low albumin and high OPG were associated with high CACS. The sensitivity of OPG for detecting CACS>200 was 80%, when the cut-off value was 1.2 ng/mL. In conclusion, CACS increased with CKD stage progression in predialysis DN patients. Serum OPG was positively associated with high CACS and can be a useful screening tool for severe coronary calcification, whereas no association between fetuin-A and CACS was found.