Paricalcitol reduces albuminuria and inflammation in chronic kidney disease - A randomized double-blind pilot trial

Vitamin D receptor activation is associated with improved survival in patients with chronic kidney disease, but the mechanism of this benefit is unclear. To better understand the effects of vitamin D on endothelial function, blood pressure, albuminuria, and inflammation in patients with chronic kidney disease ( 2 patients stage 2, remaining stage 3), we conducted a pilot trial in 24 patients who were randomly allocated equally to 3 groups to receive 0, 1, or 2 mu g of paricalcitol, a vitamin D analog, orally for 1 month. Placebo-corrected change in flow mediated dilatation with a 1-mu g dose was 0.5% and 0.4% with a 2-mu g dose ( P > 0.2). At 1 month, the treatment: baseline ratio of high sensitivity C-reactive protein was 1.5 ( 95% CI: 1.1 to 2.1; P = 0.02) with placebo, 0.8 ( 95% CI: 0.3 to 1.9; P = 0.62) with a 1-mu g dose, and 0.5 ( 95% CI: 0.3 to 0.9; P = 0. 03) with a 2-mu g dose of paricalcitol. At 1 month, the treatment: baseline ratio of 24-hour albumin excretion rate was 1.35 ( 95% CI: 1.08 to 1.69; P = 0.01) with placebo, 0.52 ( 95% CI: 0.40 to 0.69; P < 0.001) with a 1-mu g dose, and 0.54 ( 95% CI: 0.35 to 0.83; P = 0. 01) with a 2-mu g dose ( P < 0.001 for between group changes). No differences were observed in iothalamate clearance, 24- hour ambulatory blood pressure, or parathyroid hormone with treatment or on washout. Thus, paricalcitol- induced reduction in albuminuria and inflammation may be mediated independent of its effects on hemodynamics or parathyroid hormone suppression. Long- term randomized, controlled trials are required to confirm these benefits of vitamin D analogs.