Original Investigation
Pathogenesis and Treatment of Kidney Disease
Oral Calcitriol for Reduction of Proteinuria in Patients With IgA Nephropathy: A Randomized Controlled Trial

https://doi.org/10.1053/j.ajkd.2011.09.014Get rights and content

Background

Vitamin D has shown efficacy in the reduction of proteinuria in patients with chronic kidney disease. This study aimed to determine the effect of calcitriol on urinary protein excretion in patients with immunoglobulin A (IgA) nephropathy.

Study Design

Open-label, non–placebo-controlled, randomized study.

Setting & Participants

50 patients with IgA nephropathy were enrolled. The main criterion for inclusion was urinary protein excretion >0.8 g/d after renin-angiotensin system–inhibitor treatment for at least 3 months.

Intervention

Patients were randomly assigned (1:1) to receive 2 doses (0.5 μg) of calcitriol per week or no treatment for 48 weeks.

Outcomes

The primary end point was to compare change in 24-hour urinary protein excretion from baseline to last measurement during treatment.

Measurements

Every 8 weeks, there was measurement of 24-hour urinary protein excretion, serum calcium, serum phosphorus, serum creatinine, and intact parathyroid hormone.

Results

Measurement of the primary end point showed changes in urinary protein excretion of +21% (from 1.29 to 1.58 g/24 h; 95% CI, −9% to +52%) in the control group and −19% (from 1.60 to 1.30 g/24 h; 95% CI, −42% to +4%) in the calcitriol-treated group. There was a significant decrease in proteinuria in the calcitriol-treated group compared with the control group (difference between groups, 41%; 95% CI, 5%-79%; P = 0.03). The secondary end point of achieving at least a 15% decrease in proteinuria was attained by 7 of 24 (29%) controls and 17 of 26 (65%) of those treated with calcitriol (P = 0.02). No significant differences were observed in decrease in estimated glomerular filtration rate and change in blood pressure between the 2 groups. The incidence of recorded adverse events was similar between the 2 groups.

Limitations

Small and non–placebo-controlled study.

Conclusions

The addition of calcitriol to a renin-angiotensin system inhibitor resulted in a safe decrease in proteinuria in patients with IgA nephropathy.

Section snippets

Study Participants

Patients with biopsy-confirmed IgA nephropathy were enrolled from the IgA follow-up team in Peking University Institute of Nephrology. Patients 18 years and older with persistent proteinuria with protein excretion >0.8 g/d after optimal blood pressure control and full RAS inhibition for at least 3 months (in 3 consecutive samples monthly, and the last value was used as baseline calculation), eGFR (calculated by using the 4-variable MDRD [Modification of Diet in Renal Disease] Study equation19)

Demographic Data

Of 164 patients screened for eligibility, 50 were enrolled. All patients finished at least one visit after baseline. Four of these patients completed only 2-5 study visits. Three women became pregnant during the study period, and one of these women (in the calcitriol-treated group) discontinued treatment. All 3 patients discontinued ACE-inhibitor and ARB treatment after confirmation of the pregnancy. These 7 patients were included in the analysis (Fig 1). Baseline demographic, clinical, and

Discussion

In this randomized controlled trial of 50 patients, it was observed that treatment with 2 doses (0.5 μg) of calcitriol per week (with at least 3 days between 2 doses) for 48 weeks decreased proteinuria in patients with IgA nephropathy who were on stable doses of ACE inhibitors and/or ARBs, even in patients with dual inhibition of the RAS by a combination of ACE inhibitors and ARBs. Furthermore, this study showed that patients treated with calcitriol had a substantially greater likelihood of a

Acknowledgements

Support: None.

Financial Disclosure: The authors declare that they have no relevant financial interests.

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    Originally published online October 24, 2011.

    Trial registration: ClinicalTrials.gov; study number: NCT00862693.

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