Beneficial effects of better control of secondary hyperparathyroidism with paricalcitol in chronic dialysis patients

Background: Treatment of secondary hyperparathyroidism (SHPT) with calcitriol is often limited by the occurrence of hypercalcemia, hyperphosphatemia and risk of vascular calcifications. Paricalcitol, a vitamin D analogue with lower calcemic and phosphatemic effects, is successfully utilized in dialysis patients, although some uncertainty remains about the optimal dosage. Amelioration of survival in hemodialysis patients has been correlated to the use of calcitriol and, even better, paricalcitol. Methods: We evaluated 1-year treatment with paricalcitol in 12 chronic hemodialysis patients with moderate-severe SHPT previously treated with intravenous calcitriol. Starting dose of paricalcitol was calculated according to the severity of the disease by the formula: intact parathyroid hormone (iPTH) / 80, and successive titration performed according to the NKF-DOQI guidelines. Results: Paricalcitol caused a rapid decrease in serum levels of iPTH with a consistent percentage of values falling below 150 pg/mL in the first months of treatment. Although the occurrence of hypercalcemia was not significantly different between treatment with calcitriol and paricalcitol, a slight but significant increase in mean calcium levels was observed during paricalcitol treatment. A significant amelioration of erythropoiesis and acid-base balance was observed during paricalcitol treatment. Conclusions: Paricalcitol efficiently suppresses PTH secretion in dialysis patients with SHPT, with a moderate calcemic, but not a phosphatemic, effect. The dose of paricalcitol calculated as iPTH/80 may cause acute lowering of bone turnover. The improvement of anemia control and the amelioration of acid-base balance are 2 important additive effects of the better control of SHPT that may improve survival of hemodialysis patients.