Background: Vitamin D has key roles in regulating systems that could be important in the pathobiological state of proteinuria. Because of this, it could be helpful in treating patients with proteinuric renal diseases. The objective is to determine the effect of oral paricalcitol on protein excretion in patients with proteinuric chronic kidney disease.
Study design: Double-blind randomized study.
Setting & participants: 61 patients with estimated glomerular filtration rate of 15 to 90 mL/min/1.73 m(2) and protein excretion greater than 400 mg/24 h.
Intervention: Randomization to 6 months of treatment with paricalcitol, 1 mug/d, or placebo.
Outcomes & measurements: The predefined primary end point was to compare change in mean spot urinary protein-creatinine ratio between the baseline measurement and the last study evaluation (6 months in study completers) between the 2 groups. Every 4 weeks, there was measurement of serum intact parathyroid hormone, serum calcium, serum phosphorus, serum creatinine, and urine spot protein and creatinine.
Results: At baseline, mean urinary protein-creatinine ratios were 2.6 and 2.8 g/g in the placebo and paricalcitol groups, respectively. At final evaluation, mean ratios were 2.7 and 2.3, respectively. Changes in protein excretion from baseline to last evaluation were +2.9% for controls and -17.6% for the paricalcitol group (P = 0.04). A 10% decrease in proteinuria occurred in controls (7 of 27; 25.9%) and the paricalcitol group (16 of 28; 57.1%; P = 0.03).
Limitations: The relatively small sample size limits the extent to which results should be generalized.
Conclusions: Paricalcitol resulted in a significant reduction in protein excretion in patients with proteinuric renal disease.
Trial registration: ClinicalTrials.gov NCT00469625.