Association of calcium-phosphorus product with blood pressure in dialysis.

Abstract

Hypertension is very common in dialysis patients. Disorders of mineral metabolism have been linked to vascular calcification and hypertension in dialysis. Fifty-four hemodialysis patients were included in a cross-sectional study in a dialysis unit during a 6-month period. Linear regression analysis was done between averages of calcium and phosphorus (ca x ph) product and blood pressures (BPs). Ca x ph was significantly associated with systolic BP predialysis (P=.03, R=0.28), diastolic BP predialysis (P=.001, R=0.44), predialysis mean arterial pressure (MAP) (P=.002, R=0.4), and diastolic BP postdialysis (P=.03, R=0.26). No relationship was found with pulse pressures. Multilinear regression analysis was then done between ca x ph product and BPs adjusting for age, sex, hemoglobin, diabetes, albumin, parathyroid hormone, ultrafiltration volume, and average BP medications per patient. There was a strong positive association with predialysis systolic BP (P=.003, R(2)=0.49), predialysis MAP (P=.001, R(2)=0.51), and postdialysis MAP (P=.02, R(2)=0.65). No associations with pulse pressures were detected. The study findings suggest that ca x ph product is significantly associated with dialysis MAP and not pulse pressure. This is likely secondary to the stronger relationship with diastolic BP than with systolic BP. Prospective studies looking into the associated hemodynamic parameters related to arterial stiffness and endothelial dysfunction along with measures for calcifications would be very beneficial.