Funding problem.

Immunoglobulin A (IgA) nephropathy is the common type of primary glomerulonephritis in the world. A wealth of literature suggests that vitamin D and its analogs have profound effects on immune system function and glomerular mesangial cell proliferation. However, calcitriol, the standard form of vitamin D, carries a substantial risk of hypercalcemia. Recently, paricalcitol (19-nor-1,25-dihydroxyvitamin D2) was approved for the treatment of secondary hyperparathyroidism in chronic renal failure, and the incidence of hypercalcemia is much lower than calcitriol. Therefore, the investigators plan to conduct a randomized cross-over study to evaluate the efficacy of paricalcitol in the treatment of IgA nephropathy. Thirty patients with biopsy-proven IgA nephropathy will be recruited. They will be randomized to paricalcitol for 12 weeks or no treatment, followed by cross over to the other arm after a washout period. Proteinuria, renal function, serum and urinary inflammatory markers will be monitored. This study will explore the potential anti-proteinuric and anti-inflammatory effects of paricalcitol in the treatment of IgA nephropathy, which has no specific treatment at present.

Inclusion Criteria:

• aged 18-65 years
• biopsy-confirmed IgA nephropathy
• proteinuria > 1 g/day (or proteinuria > 1 g/g-Cr) in 3 consecutive samples within 12 weeks despite ACE inhibitor or angiotensin receptor blocker treatment (e.g. ramipril 5 mg daily, lisinopril 10 mg daily, or valsartan 80 mg daily) for at least 3 months
• estimated glomerular filtration rate > 60 ml/min/1.73m2
• corrected serum calcium level > or = 2.45 mmol/l
• willingness to give written consent and comply with the study protocol

Exclusion Criteria:

• Pregnancy, lactating or childbearing potential without effective method of birth control
• Severe gastrointestinal disorders that interfere with their ability to receive or absorb oral medication
• History of malignancy, including leukemia and lymphoma within the past 2 years
• Systemic infection requiring therapy at study entry
• Any other severe coexisting disease such as, but not limited to, chronic liver disease, myocardial infarction, cerebrovascular accident, malignant hypertension
• History of drug or alcohol abuse within past 2 years
• Participation in any previous trial on paricalcitol
• Patients receiving treatment of vitamin D and/or its analogue for other medical reasons within the past 3 months
• Patients receiving treatment of corticosteroid
• On other investigational drugs within last 30 days
• History of a psychological illness or condition such as to interfere with the patient's ability to understand the requirement of the study
• History of non-compliance
• Known history of sensitivity or allergy to paricalcitol or other vitamin D analogs