The objective of this study is to determine whether paricalcitol is safe and effective compared to placebo in reducing elevated serum PTH levels in patients with chronic kidney disease.

Inclusion Criteria:

• Under care of physician at least 2 months (for CKD)

• Not on active Vitamin D therapy for at least 4 weeks prior

• If female:

  • Not of childbearing potential, OR,
  • Practicing birth control
  • Not breastfeeding

• If taking phosphate binders, on a stable regimen at least 4 weeks prior

• For entry into Pretreatment Phase:

  • iPTH at least 120 pg/mL
  • GFR of 15-60 mL/min and no dialysis expected for at least 6 months

• For entry into Treatment Phase:

  • Average of 2 consecutive iPTH values of at least 150 pg/mL, taken at least 1 day apart (all values not less than 120 pg/mL_
  • 2 consecutive corrected serum calcium levels between 8.0-10.0 mg/dL
  • 2 consecutive serum phosphorus levels of not more than 5.2 mg/mL

Exclusion Criteria:

• History of allergic reaction or sensitivity to similar drugs
• Acute Renal Failure within 12 weeks of study
• Chronic gastrointestinal disease
• Spot urine result demonstrating a urine-calcium-to-urine creatinine ratio of greater than 0,2, or a history of renal stones
• Taken aluminum-containing phosphate binders within last 12 weeks, or requires such medication for more than 3 weeks during study
• Current malignancy, or clinically significant liver disease
• Active granulomatous disease (TB, sarcoidosis, etc.)
• History of drug or alcohol abuse within 6 months prior
• Evidence of poor compliance with diet or medication
• Received any investigational drug or participated in any device trial within 30 days prior
• Taking maintenance calcitonin, bisphosphonates, or drugs that may affect calcium or bone metabolism (other than females on stable estrogen and/or progestin therapy)
• On glucocorticoids for a period of more than 14 days within the last 6 months
• HIV positive