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Differential Diagnosis: Hyperphosphatemia

Julie Allen, BVMS, MS, MRCVS, DACVIM (SAIM), DACVP, Cornell University

Internal Medicine

|December 2019|Peer Reviewed

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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.


For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

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