Hyperphosphatemia is defined as an elevated level of circulating phosphorus (Pi).
Normal canine blood levels of phosphorus are 2.5 - 7.7 mg/dL.
Physiologically elevated serum and plasma Pi concentrations are commonly noticed in rapidly growing large pups due to enhanced intestinal phosphorus uptake and decreased renal phosphorus excretion.
Pathologically causes of hyperphosphatemia include:
- - Chronic renal disease - due to decreased phosphorus excretion as a result of hyperparathyroidism
- - hypoparathyroidism - due to increased renal phosphorus reabsorption
- - hypothyroidism
- - unbalanced homemade diets deficient in phosphorus
- - vacuolar hepatopathy
- Trauma - causing tissue release of phosphorus
- Spurious - hemolysis
- - ingestion of grapes or raisins
- - vitamin D toxicosis
- - xylitol toxicosis
- - Allopurinol associated with treatment of Leishmania spp
With vitamin D toxicosis in dogs, a concurrent hypercalcemia is commonly observed.
In chronic severe cases, concomitant hypocalcemia may result from precipitation of excessive phosphorus with calcium and cause muscle fasciculations and tetanic muscle contractions. In sustained cases, precipitation of calcium-phosphate salts results in extraskeletal tissue mineralization with a potentially fatal outcome.
Treatment is dependent upon underlying cause, but management of hyperphopsphatemia involves aggressive intravenous fluid therapy, low phosphate diets and oral phosphate binders.
Fluids devoid of calcium such as physiologic saline such as isotonic saline solution (0.9% sodium chloride) is recommended.
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