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Differential Diagnosis: Hypokalemia

Julie Allen, BVMS, MS, MRCVS, DACVIM (SAIM), DACVP (Clinical), Durham, North Carolina

Internal Medicine

|October 2019|Peer Reviewed

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Editor's note: A previous version of this article incorrectly listed hyperkalemic periodic paralysis in Burmese cats as a differential diagnosis. This has been corrected as of February 2020.

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

  • Increased loss
    • Through the kidney (most common)
      • Chronic kidney disease
      • Loop and thiazide diuretics
      • Postobstructive diuresis (cats affected more than dogs)
      • Renal tubular disease
      • Osmotic diuresis
      • Acute metabolic acidosis secondary to lactic acid or ketone excretion
      • Primary metabolic alkalosis
      • Diuresis secondary to hyperadrenocorticism; some patients with adrenocortical tumors also produce excess aldosterone
      • High dietary sodium intake
      • Primary hyperaldosteronism, usually due to an adrenal tumor or hyperplasia
      • Excessive mineralocorticoid administration (eg, overdose of desoxycorticosterone pivalate or fludrocortisone)
      • Administration of certain drugs (eg, penicillins, carbonic anhydrase inhibitors, amphotericin B)
    • Through the GI tract
      • Vomiting
      • Chronic diarrhea
      • Ileus
    • Third-spacing (eg, loss in peritoneal fluid)
  • Transcellular shifts
    • Insulin release or administration
    • Increased endogenous catecholamines (eg, pheochromocytoma) or epinephrine administration
    • Primary respiratory or metabolic alkalosis
    • Hyperthyroidism, likely due to transcellular shifts
    • Endotoxemia
    • Refeeding syndrome
    • Hypomagnesemia
    • Treatment with or toxicosis from β2 agonists (eg, albuterol, terbutaline)
    • Hyperinsulinemia secondary to xylitol toxicosis, which stimulates the activity of the Na+/K+-ATPase pump, which catalyzes transfer of potassium in the cells
    • Hypothermia
    • Periodic hypokalemic polymyopathy (Burmese cats)
  • Decreased intake
    • Administration of low-/no-potassium intravenous fluids
    • Low-potassium diets, often acidifying diets
    • Severe anorexia (usually a confounding factor and not a primary cause)
    • Ingestion of clay cat litter containing bentonite, which binds potassium in the GI tract
  • Pseudohypokalemia; occurs secondary to lipemia and marked hyperglobulinemia*
*Only when measured by indirect potentiometry, the method used by most chemistry analyzers; blood gas analyzers using direct potentiometry are unaffected.


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

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