Paricalcitol reduces proteinuria but does not modify peritoneal protein loss in patients on peritoneal dialysis

Introduction: Paricalcitol, a selective activator of Vitamin D receptors, is successfully used as a treatment of hyperparathyroidism secondary to chronic kidney disease (CKD). In addition, it has been proposed for reducing proteinuria in patients with CKD. Nonetheless, little is known about its effect on peritoneal protein loss in patients on peritoneal dialysis (PD). Objectives: To analyse the efficiency of oral paricalcitol in secondary hyperparathyroidism control in PD patients and to verify its effect on urinary and peritoneal effluent protein loss. Material and method: Prospective study with a 12-month follow-up on a cohort of PD patients. Invention consisted of the introduction of paricalcitol for the treatment of secondary hyperparathyroidism. Paricalcitol was dosed according to parathyroid hormone (PTH); therefore, if PTH was lower than 500pg/ml, each patient was given a capsule of 1 mg/day; if the PTH was higher than this amount, a dose of 2mg/day was administered. Epidemiological, clinical and analytical data were analysed. Results: 38 patients (56 +/- 19 years, 55% women, 16% diabetics, technique time (14 +/- 10 months) were included in the study. Thirty-three of them received 1mg/day of paricalcitol; the rest received 2mg/day. The use of paricalcitol was associated with a PTH decrease of 30.7 +/- 6.8% (P<.001) after 12 months of treatment with no changes in calcium (8.82 +/- 0.96 vs. 9.02 +/- 0.91; P=.153) and phosphate levels (4.78 +/- 0.63 vs. 4.93 +/- 0.77; P=.693). Patients did not modify treatment concurrent with phosphate binders over the study period, nor did they change the cinacalcet dosage. However, less patients needed it by the end of the study. The PTH baseline levels were independent indicators of its decrease (b=0.689, P=.018), and the rest of the analysed parameters were not affected. Over the study period there was a proteinuria decrease (0.79 +/- 0.41 vs. 0.64 +/- 0.36g/day, P=.034) with no changes in renal function (7.2 +/- 1.1 vs. 6.3 +/- 0.9ml/min, P=.104)in terms of the percentages of patients taking renin-angiotensin system inhibitors (71 vs. 68 %, P=.472) neither in the planned dosages. There was no modification in peritoneal protein loss (5.8 +/- 1.9 vs. 6.0 +/- 2.2g/24h, P=.731) nor in serum albumin levels (3.7 +/- 1.1 vs. 3.7 +/- 1.2g/dl, P=.697). Conclusions: The use of oral paricalcitol substantially reduces and ensures PTH levels in patients on PD. Their use is associated with a proteinuria decrease and is not linked to a decrease of glomerular filtration rate nor to changes in the medication that could modify it. We have found no modification in the quantification of peritoneal protein loss.