Anti-proteinuric Effect of Calcitriol in Non-diabetic Kidney Disease Patients

Inclusion Criteria: * Nondiabetic kidney disease patients aged 19-70 years * MDRD GFR ≥ 30 mL/min/1.73m2 * Patients with residual urine protein/creatinine ratio \> 200 mg/g * Adequate blood pressure control as treated systolic blood pressure \<=140 or diastolic \<=90 mmHg with RAS inhibitor for more than 3 months * Normotensive patients untreated with RAS inhibitors * Serum intact PTH as 35-500 mg/dL and serum calcium less than 10.2 mg/dL * Patients who have not been treated vitamin D within the 3 months prior to signing the informed consent form Exclusion Criteria: * Patients with nephrotic-range proteinuria (24 hour urine protein \>3.5 g/24 hr) * Patients with rapidly progressive glomerulonephritis * Patients requiring renal replacement therapy immediately * Hypercalcemia (uncorrected serum calcium level \> 10.2 mg/dL) within 3 months * Malignant hypertension * Heart failure (New York Heart Association \[NYHA\] functional class II to IV or LVEF less than 40%) * Severe chronic obstructive lung disease * Decompensated liver disease * Known allergy or hypersensitivity to vitamin D * Current treatment with steroids and/or immunosuppressive agents * No other active primary malignancy requiring treatment or that limits survival to ≤ 2 years * History of noncompliance to medical regimen * Inability to give an informed consent or to cooperate with researchers (e.g., psychiatric disorder)