Young, growing dogs can have higher phosphorus levels due to increased growth hormone in their systems and increased need for phosphorus for bone development. Older dogs are more likely to have diseases that will eventually lead to the development of chronic hyperphosphatemia.
Kidney disease is the most common cause of hyperphosphatemia in dogs. However, it can also be related to increased absorption of phosphorus through the gastrointestinal tract or through transcellular shifting (transport of solutes by a cell through a cell) of phosphorus, usually from bone.
Hyperphosphatemia can also be related to:
- Vitamin D toxicity
- Enema intoxication through the use of phosphate-containing enemas
- Urinary tract obstruction
- Endocrinopathies (hyperthyroidism, hypoparathyroidism, hypoadrenocorticism)
- Cancer
- Nutritional supplementation
- Bladder rupture
- Bone or muscle disease
- Xylitol intoxication
- Snakebites
- Acromegaly (overproduction of growth hormone)
Occasionally, phosphorus will be elevated in cases of serious trauma or in conditions such as acute tumor lysis syndrome (seen most commonly with end stage tumors) and rhabdomyolysis, which is a muscular disorder.
