Objective: We investigated whether disturbance of calcium and phosphate metabolism is associated with the presence and severity of calcific aortic valve disease (CAVD) in patients with normal or mildly impaired renal function.
Methods: We measured serum levels of calcium, phosphate, alkaline phosphatase (AKP), intact parathyroid hormone (iPTH), 25-hydroxyvitamin D (25-OHD), and biomarkers of bone turnover in 260 consecutive patients with normal or mildly impaired renal function and aortic valve sclerosis (AVSc) (n=164) or stenosis (AVS) (n=96) and in 164 age- and gender-matched controls. Logistic regression models were used to determine the association of mineral metabolism parameters with the presence and severity of CAVD.
Results: Stepwise increases were observed in serum levels of calcium, phosphate, AKP, and iPTH from the control group to patients with AVS, and with reverse changes for 25-OHD levels (all P<0.001). Similarly, osteocalcin, procollagen I N-terminal peptide, and β-isomerized type I collagen C-telopeptide breakdown products were significantly increased stepwise from the control group to patients with AVS (all P<0.001). In patients with AVS, serum levels of iPTH were positively, in contrast 25-OHD levels were negatively, related to trans-aortic peak flow velocity and mean pressure gradient. After adjusting for relevant confounding variables, increased serum levels of calcium, phosphate, AKP, and iPTH and reduced serum levels of 25-OHD were independently associated with the presence and severity of CAVD.
Conclusions: This study suggests an association between mineral metabolism disturbance and the presence and severity of CAVD in patients with normal or mildly impaired renal function. Abnormal bone turnover may be a potential mechanism.
Keywords: Aortic stenosis; Calcium; Mineral metabolism; Phosphate; Valve heart disease.