The Effect of Paricalcitol on Creatinine Filtration, Secretion and Glomerular Filtration Rate

The Effect of Paricalcitol on Creatinine Filtration, Secretion and Glomerular Filtration Rate

The purpose of this study is to study the effects of Paricalcitol (Zemplar) on kidney functioning. The investigators hypothesize that the increase in serum creatinine observed in recent paricalcitol trials is a function of reduced creatinine secretion and not an actual reduction in kidney function. 16 patients will have kidney function measured via iothalamate clearance at baseline, after 7 days of paricalcitol treatment and after 7 days of being washed off the paricalcitol.

Inclusion Criteria:

• Age > 18 years
• Stage 3 or 4 CKD
• Ability to give informed consent

Exclusion Criteria:

• Serum Calcium > 10 g/dL
• Serum Phosphorous > 6 g/dL
• On > 400 units/d Vitamin D therapy
• Receiving cimetidine, triamterene, or trimethoprim, drugs that block creatinine secretion
• On vitamin D receptor activators (paricalcitol, calcitriol or Zemplar)
• Allergic to radiocontrast dye