Effects of oral paricalcitol on hyperparathyroidism and proteinuria in peritoneal dialysis patients.

Severe secondary hyperparathyroidism is a complication of chronic kidney disease. Paricalcitol is a vitamin D receptor activator with efficacy in the treatment of hyperparathyroidism that also has the minor side effects of hypercalcemia and hyperphosphatemia. As a pleiotropic effect, paricalcitol reduces proteinuria in patients with chronic kidney disease stages 2-4. Oral paricalcitol offers an alternative way to treat hyperparathyroidism and proteinuria in peritoneal dialysis patients. Our prospective study enrolled 18 patients with hyperparathyroidism (6 with diabetes also) who were given oral paricalcitol at initial dose of 1-2 microg daily, depending on their level of intact parathyroid hormone (iPTH). In the 1st month, iPTH levels declinedsignificantly to 295 +/- 147 pg/mL from 670 +/- 318 pg/mL, and by the 3rd month, they declined to 192 +/- 340 pg/mL (p < 0.001). Without modifications to doses of angiotensin converting-enzyme inhibitor or angiotensin II receptor blocker, proteinuria declined in the 1st month to 1.41 +/- 1.5 g/L from 1.68 +/- 1.7 (p = 0.006) and, in the 3rd month, without statistical significance. In some patients, the dose of paricalcitol was reduced because of iPTH levels that were too low at 1 month. The patients whose doses of paricalcitol were maintained at 3 months showed a reduction in proteinuria to 2.1 +/- 2.1 g/L daily from 3.1 +/- 2. 7 g/L (p = 0.04) and to 2.3 +/- 2.1 g/day from 5.0 +/- 6.1 g/day (p = 0.012). In conclusion, paricalcitol is effective for treating hyperparathyroidism in patients on peritoneal dialysis and seems also to have an antiproteinuric effect in these patients.