Management of Mineral and Bone Disease in Hemodialysis-Calcitriol vs. Paricalcitol

Active vitamin D analogs have been the mainstay of treatment for patients on hemodialysis
with mineral and bone disease (MBD) for the past decade. Intravenous calcitriol is an active
vitamin D analog which is nearly identical to natural 1, 25 Vitamin D3. Calcitriol results
from the hydroxylation of previtamin D3 in the liver and kidney. Paricalcitol, 19-nor-1 ,
25-dihydroxyvitamin D2, is a newer agent vitamin D analog. This agent is believed to have an
effect more specific to the parathyroid gland, and less specific to absorption of calcium
and phosphorus from the gut. Although both formulations appear equally effective in
suppressing parathyroid hormone (PTH), studies have suggested a greater calcemic effect with
intravenous calcitriol as compared to paricalcitol (1). Due to this, paricalcitol is the
predominant active vitamin D analog used in hemodialysis patients in the United States. Two
recent changes in the management of hemodialysis patients will likely reduce the amount of
active vitamin D analogs used in the near future: the liberalization of PTH goals according
to international guidelines, (2) and the implementation of bundled payments for dialysis by
Medicare. These changes challenge previous studies that have analyzed the safety and
efficacy of these medications. The purpose of this prospective, randomized, cross-over study
will be to determine whether calcitriol is as safe and effective as paricalcitol in the
treatment of MBD in hemodialysis patients using the revised KDIGO parathyroid hormone
targets. Our hypothesis is that calcitriol will be as equally safe and effective as
paricalcitol in the treatment of MBD in hemodialysis patients.

Inclusion Criteria:

- All subjects will have been treated for at least three months on hemodialysis with IV
paricalcitol. These subjects must have a most recent calcium level within the normal
range, most recent phosphorus level < 8 mg/dL and a most recent PTH between 130-585 pg/mL

Exclusion Criteria:

Patients will be excluded if:

1. age greater than 18

2. active malignancy

3. expected survival greater than 6 months

4. high likelihood of renal transplant during the study period.

5. Low calcium bath

6. prior parathyroidectomy

7. use of calcimimetics