Cholecalciferol Versus Doxercalciferol in the Treatment of Secondary Hyperparathyroidism in Chronic Kidney Disease

Comparison of Cholecalciferol Versus Doxercalciferol in the Treatment of Secondary Hyperparathyroidism in CKD

The majority of patients with moderate to severe chronic kidney disease (CKD) (stages 3 and 4) develop secondary hyperparathyroidism (2°HPT), but the optimal therapy to control hyperparathyroidism in this group is unknown. The National Kidney Foundation presented guidelines in 2003 recommending vitamin D supplementation for vitamin D insufficient patients and active vitamin D therapy in patients with sufficient levels. These guidelines are based on opinion since there are no significant trials to determine if vitamin D supplementation is effective in this population. The active vitamin D metabolites doxercalciferol, paricalcitol, and calcitriol have been shown to effectively suppress parathyroid hormone (PTH), but have not been compared with vitamin D supplementation with a calciferol (ergocalciferol or cholecalciferol). Beyond hyperparathyroidism, small studies suggest vitamin D replacement in vitamin D insufficient non-CKD subjects result in improved pain, feeling of well being, blood pressure and strength. In this proposed study we wish to directly compare the effectiveness of cholecalciferol versus doxercalciferol in suppressing elevated PTH levels in subjects with CKD not on dialysis who have vitamin D insufficiency in a three month study. Secondary endpoints will be change in blood pressure.

Patients with CKD stage 3 were randomly allocated (by blinded group allocation) to either cholecalciferol (4000 U per day for one month then 2000 IU daily thereafter) or doxercalciferol (2.5 mcg po daily. Assessments for blood endpoints (primary end point PTH; secondary calcium, phosphorus) were done monthly. Other assessments (blood pressure) were done at baseline and at 3 months.

Inclusion Criteria:

• age 18 years old or older, male or female
• able to sign informed consent
• CKD stage 3 (GFR 30-59 ml/min) or stage 4 (15-29 ml/min)
• intact Parathyroid hormone level (iPTH) > 100 pg/ml for stage 3 or iPTH > 150 pg/ml for stage 4
• calcidiol levels ≤ 20 ng/ml
• ability to ambulate without assistance

Exclusion Criteria:

• intact PTH > 400 pg/ml
• initial corrected Calcium > 9.7 mg/dl
• initial serum Phosphorous > 5.0 mg/dl
• initial standardized blood pressure of > 160/100
• history of significant liver disease or cirrhosis
• anticipated requirement for dialysis in 6 months
• malabsorption, severe chronic diarrhea, or ileostomy
• no calcimimetic or active vitamin D therapy 30 days prior to enrollment
• use of digoxin, magnesium containing products, mineral oil, or cholestyramine