The purpose of this study is to demonstrate the safety and effectiveness of Hectorol® (doxercalciferol) capsules in treating patients with Stage 3 or Stage 4 chronic kidney disease (CKD) with secondary hyperparathyroidism who have vitamin D levels in the normal range. Previous studies with doxercalciferol were conducted in patients who had low levels of vitamin D.

Inclusion Criteria:

• Plasma iPTH value above 110 pg/mL for CKD Stage 3 subjects or above 150 pg/mL for CKD Stage 4
• Serum 25-hydroxyvitamin D level greater than or equal to 30 ng/mL
• CKD Stage 3 evidenced by a glomerular filtration rate (GFR) from the abbreviated MDRD equation between 30-59 mL/min or CKD Stage 4 evidenced by a glomerular filtration rate (GFR) from the abbreviated MDRD equation between 15-29 mL/min

Exclusion Criteria:

• Serum cCa > 9.5 mg/dL
• Serum P > 4.6 mg/dL
• Abnormal liver functions
• Anticipated requirement for maintenance hemodialysis
• Use of active vitamin D sterol therapy