Hypocalcemia
Hypocalcemia
Serum calcium levels are normally tightly regulated by the combined actions of calcitriol and PTH. Hypocalcemia can, however, occur in some dogs with CRF as a result of.
Decreased intestinal absorption due to low calcitriol levels, Decreased dietary intake due to anorexia, Deposition of calcium-phosphate complex in tissues, which reduces serum ionised calcium.
Elevated serum calcium may be present in some advanced cases of CRF, because the negative feedback mechanism by which hypercalcemia suppresses PTH secretion, is impaired at low calcitriol concentrations.
Management
Dietary manipulation is the cornerstone in the conservative medical management of CRF, but this represents only one aspect of the therapeutic strategy. Where an underlying primary disease has been identified, or if pre- or post-renal components are involved, specific therapy to correct these may be required.
Where appropriate, additional supportive measures may include:
- Avoidance of stress
- Supplementation with calcitriol and calcium
Dietary Management
Calcium
Calcium per se does not affect progression of renal failure, although a decrease in serum ionized calcium levels may contribute to increased PTH release.
Recommendations in man, suggest that the calcium-phosphorus product [Ca x P] in the blood should not exceed 55 mg/dl, as this may promote soft tissue calcification and lead to further progression of renal disease. This may equally apply to dogs, and calcium should therefore only be supplemented in individuals who are not hypercalcemic.
Serum calcium levels may be low, normal, or high in dogs with CRF. Therefore dietary calcium levels should be adjusted to suit the individual patient; whereas calcium supplementation may be required in hypocalcemic individuals and is contraindicated in the presence of hypercalcemia.