Calcitriol for Chronic Renal Failure

Uses/Indications: Controlling phosphate levels and preventing or reversing secondary hyperparathyroidism in dogs and cats suffering with chronic renal failure (CRF).

Studies: A salutary effect of calcitriol treatment of CRF was shown in a placebo-controlled study of 37 dogs. The dose of calcitriol was adjusted according to serial ionized calcium and PTH determinations, and ranged from 0.75 to 5.0 ng/kg/day. Over the course of 1 year, there was a significant reduction in mortality rate in the group of dogs receiving calcitriol (28%) as compared to the placebo group (63% mortality). In dogs receiving calcitriol, the median survival time was 365 days, as compared to a median survival time of 250 days in those receiving a placebo (Polzin et al. 2005). Thus, calcitriol therapy appears to have clinical benefit in dogs with chronic kidney disease. Similar studies were done in cats by the same investigators who concluded that there is no advantage to calcitriol treatments in cats with CRF, but the study followed cats for just one year. In order to show a difference in treatment effect if one exists, studies in cats with CRF must be conducted for at least 2 and possibly 3 years due to the inherently slow nature of the progression of chronic renal disease in this species.

Adverse Effects: Hypercalcemia – polydipsia, polyuria, and anorexia

Hypocalcemia – muscle tremors, twitching, tetany, weakness, stiff gait, ataxia, seizures

Hyperphosphatemia

Dosing: Dogs/Cats – 1.65ng to 3.63ng/kg PO daily **Oil Suspension stable up to 180 days**

**Serum phosphorous should be less than 6mg/ml before calcitriol initiation**

Monitoring Parameters: 1. Serum calcium, phosphate, creatinine. Baseline and at 1 week and 1 month after starting treatment, then monthly. 2. Urine calcium baseline and as needed. 3. Serum PTH levels

Polzin, D., S. Ross, C. Osborne, et al. 2005. Clinical benefit of calcitriol in canine chronic kidney disease [abstract]. Journal of Veterinary Internal Medicine 19: 433.