Differential Diagnosis: Hypokalemia

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.