Background: Chronic kidney disease (CKD) patients are at a high risk of dying from a cardiovascular event, mainly due to coronary calcification. Among the various uremic and dialysis-specific risk factors for coronary calcification are mineral metabolism disorders. The role that secondary hyperparathyroidism (SHPT) consequent to the altered calcium and phosphate metabolism plays in the pathogenesis of coronary calcification remains unclear. The aim of this study was to evaluate the prevalence of coronary artery calcification in dialysis patients with severe SHPT submitted to multislice coronary tomography (MSCT) and to identify risk factors for coronary calcification.
Methods: This study involved 23 adult dialysis patients (age >18 years) with severe SHPT who were candidates for parathyroidectomy (PTX). All were submitted to MSCT and bone densitometry during the month preceding PTX. Fasting blood samples were collected immediately before surgery. Markers of mineral metabolism, including ionized calcium, phosphorus, alkaline phosphatase, intact-parathyroid hormone (iPTH), osteoprotegerin (OPG) and soluble receptor activator of nuclear factor-kappaB ligand, were analyzed. Dyslipidemia was assessed by determination of LDL, HDL and VLDL-cholesterol and triglyceride levels. Agatston units (AU) were used to calculate calcium scores.
Results: No coronary calcification was found in 30% of the patients. Moderate (calcium score > 100 AU) and severe (calcium score >400 AU) calcification was observed in 12 and 36% of the patients, respectively. In the univariate analysis, calcium volume correlated positively with VLDL-cholesterol (r = 0.44; p = 0.03) and, albeit less than significantly, with age (r = 0.35; p = 0.09), triglycerides (r = 0.39; p = 0.05) and Framingham risk index (r = 0.37; p = 0.07). We also found that OPG correlated negatively with bone mineral density at the L2-L4 lumbar vertebrae (r = -0.54; p = 0.007) and femoral neck (r = -0.43; p = 0.04).
Conclusions: Although high levels of PTH should be considered a risk factor for cardiovascular death, the real role of severe SHPT on coronary calcification is to be clarified.