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For further information, see CMDT Part 21-05: Hyperkalemia

Key Features

Essentials of Diagnosis

  • Serum potassium > 5.2 mEq/L (> 5.2 mmol/L)

  • Hyperkalemia may develop from angiotensin-converting enzyme (ACE) inhibitors, angiotensin-receptor blockers (ARBs), and potassium-sparing diuretics, most commonly in patients with kidney dysfunction

  • The ECG may be normal despite life-threatening hyperkalemia

  • Rule out pseudohyperkalemia and extracellular potassium shift from the cells

General Considerations

  • Persistent hyperkalemia is generally due to

    • Impaired renal potassium excretion from low aldosterone effect (either decreased secretion of aldosterone or decreased responsiveness) or

    • Impaired delivery of sodium and water to the distal nephron or

    • Kidney disease (acute or chronic)

    • See Table 21–4

  • Transient hyperkalemia

    • Shift of intracellular potassium to the extracellular fluid

    • Occurs with tissue damage (rhabdomyolysis, tumor lysis, massive hemolysis, and trauma) or metabolic acidosis

Table 21–4.Causes of hyperkalemia.


Increased potassium release from cells

  • Pseudohyperkalemia (Table 21–4)

    • Leakage from marked thrombocytosis (> 500,000/mcL [500 × 109/L]) or leukocytosis (>100,000/mcL [100 × 109/L]), particularly leukemic cells

    • During phlebotomy

      • Fist clenching, application of tourniquets, using small bore needles

      • Presence of hemolysis in the processed sample suggests these etiologies.

  • Tissue breakdown

    • Tissue damage results in release of intracellular potassium to the extracellular space (rhabdomyolysis, tumor lysis, massive hemolysis, and trauma)

    • Hyperkalemia is more common when there is concurrent renal impairment

  • Hyperglycemia

    • Hyperkalemia may occur with uncontrolled diabetes, even if total body potassium is low

    • Due to a combination of insulin deficiency and hyperosmolarity

  • Metabolic acidosis

    • Serum potassium concentration rises ~ 0.7 mEq/L for every decrease of 0.1 pH unit

    • This effect is not seen with organic acidosis, such as lactic acidosis or ketoacidosis

Impaired kidney excretion

  • Acute kidney injury

    • Poor renal excretion of potassium from rapid reduction of kidney function

    • Hyperkalemia occurs more commonly in oliguric patients

  • Chronic kidney disease

    • Normal serum potassium generally preserved until GFR declines to < 20–30 mL/min/1.73 m2

    • Hyperkalemia with more modest decline in GFR is often ...

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