Differential Diagnosis: Hyperphosphatemia

Following are differential diagnoses, listed in order of likelihood, for patients presented with hyperphosphatemia.

• Pseudohyperphosphatemia

  • In vitro hemolysis

  • Hyperglobulinemia due to monoclonal gammopathy

• Physiologic response

  • Mild increase (normal in young animals)

  • Mild postprandial increase

• Decreased renal excretion

  • Decreased glomerular filtration rate (prerenal, renal, or postrenal)

  • Uroabdomen

  • Primary hypoparathyroidism

  • Hyperthyroidism

  • Acromegaly

• Increased GI absorption

  • Hypervitaminosis D (eg, cholecalciferol or calcipotriene toxicity)

  • Granulomatous disease

  • Phosphate enemas

  • Phosphate-containing urinary acidifiers

  • Devitalized intestine

• Transcellular shift (intracellular to extracellular fluid)

  • Metabolic acidosis

  • Myopathies

  • Arterial thromboembolism

  • Acute tumor lysis syndrome

• Xylitol toxicosis*

*Although patients may initially be hypophosphatemic due to increased insulin within the first 12 hours, liver failure-associated hyperphosphatemia can occur due to an unknown mechanism and has been associated with a poor prognosis.