Introduction
- Definition : serum inorganic phosphate >2.00 mmol/l.
- Phosphate is the major intracellular anion. Has structural role in cell membranes, hydroxyapatite of bone, nucleic acids and phosphoproteins including adenosine triphosphate (ATP). Important in oxygen transports (2,3-diphosphoglycerate), second messenger systems (cyclic adenosine monophosphate), coenzyme systems (nicotinamide adenine dinucleotide phosphate). Important in the regulation of protein, fat and carbohydrate metabolism. Involved in the activation of vitamin D and calcium homeostasis.
- Phosphorus exists as organic (phospholipids, phosphate esters) and inorganic (orthophosphoric acid, pyrophosphoric acid) forms. 80-90% of total body phosphate is inorganic in bone as hydroxyapatite. 15% is organic and in soft tissues. Most serum phosphorus is inorganic orthophosphoric acid. 10-20% of inorganic is protein bound. 80-90% is free or bound to magnesium, sodium and calcium.
- <1% of total body phosphate found as extracellular active forms with only 33% of this being ionized.
- Total body phosphate levels closely regulated in conjunction with calcium.
Diagnosis
Clinical signs
- See Presenting Signs.
Diagnosis
Differential diagnosis
- Physiologic hyperphosphatemia in young animals.
- Laboratory error due to lipemia or hemolysis.
Sources
Publications
Refereed papers
- Recent references from PubMed.
- Schropp D M & Kovacic J (2007) Phosphorus and phosphate metabolism in veterinary patients. J Vet Emerg Crit Care 17 , 127-134
Other sources of information
- Marino P (2007) Renal and Electrolyte Disorders: Calcium and Phosphorus. In: The ICU Book.pp 639-655. Lippincott, Williams & Wilkins.
- DiBartola S P, Willard M D (2006) Disorders of Phosphorus: Hypophosphataemia and Hyperphosphataemia. In: Fluid, Electrolyte, and Acid-Base Disorders Disorders in Small Animal Practice.pp 195-209. Ed. S DiBartola, Saunders Elsevier.
