General Design
* Open label, active comparator, multicenter, parallel group, phase 4 study of paricalcitol versus calcitriol for suppression of PTH in stage 3 and 4 CKD patients with SHPT.
* Total study duration is 26 weeks (1 week screening, 24 weeks active medications, 1 week follow up.
* Patients meeting inclusion/exclusion criteria including baseline laboratory results will be randomized to paricalcitol or calcitriol, and enter a 24 weeks treatment phase. Visits, including safety and efficacy laboratory tests will be at weeks 4, 8, 12, 18, and 24. A follow up visit will be performed 1 week after stopping study medication.
