Calcitriol in the Treatment of Immunoglobulin A Nephropathy

Inclusion Criteria: * Aged 18-65 years * Biopsy-confirmed IgA nephropathy * Proteinuria \> 0.8 g/day in 3 consecutive samples within 12 weeks despite ACE inhibitor or angiotensin receptor blocker treatment for at least 3 months or 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