Abstract:
Background : Proteinuria is the one of the most important independent risk factors for progression of chronic kidney disease (CKD). These are no available data regarding the role of natural vitamin D with/without active vitamin D on proteinuria and renal function in CKD patients with vitamin D insufficiency/deficiency. This study was conducted to explore the additional effect of both active vitamin D (calcitriol) and natural vitamin D (ergocalciferol) on proteinuria and kidney function in CKD with vitamin D insufficiency/deficiency Methods: This is the first double-blind, randomized placebo-controlled trial to answer the question. Sixty eight patients with estimated glomerular filtration rate (eGFR) between 15 to 60 mL/min/1.73m2, urine protein to creatinine ratio (UPCR) greater than 1 g/g, and vitamin D insufficiency/deficiency (25OH-D level<30 ng/mL) were enrolled. Patients were randomly assigned to receive 12-week treatment with oral ergocalciferol (20,000 unit twice weekly) plus placebo (n=36) or ergocalciferol plus oral calcitriol (0.5 mcg twice weekly)(n=32). Results: The mean baseline UPCR of both groups were comparable (3.6 ± 3.8 g/g in combined group and 3.5±3.0 g/g in ergocalciferol group). Following 12 -week treatment, there were marked reductions in UPCR of both groups (2.3± 2.1 g/g in combined group and 2.4± 2.0 g/g in ergocalciferol group). The percentage reductions in UPCR of both groups were not significantly different (-25.5% in combined group and -23.7% in ergocalciferol group). More than 50% of patients had 30% reduction on proteinuria in both groups (56.3% in combined group and 52.8% in ergocalciferol group).These effects were more robust in diabetic nephropathy (-29.7%) and nephrotic range proteinuria (-33.4%). The mean eGFR and blood pressure did not differ between baseline and 12-week follow up and between both groups. No severe hypercalcemia or serious side effects were noted in both groups. Conclusions : This is the first study which illustrates the proteinuria lowering effect of ergocalciferol with or without calcitriol in CKD patients with vitamin D insufficiency/deficiency, particularly in diabetic nephropathy and nephritic range proteinuria. A longer study is required to examine the renal function retardation effect of ergocalciferol with/without calcitriol treatment.