Hyperkalemia

Decreased renal potassium retention

• ACE inhibitors, ARBs, aldosterone antagonists (spironolactone)

• Pseudohypoaldosteronism or true hypoaldosteronism

• Congenital adrenal hyperplasia

• Kidney failure

Excessive potassium intake

• Generally occurs in setting of comorbid disorder (e.g., kidney insufficiency) as kidney can usually handle large potassium load

• IV fluids

• Hyperalimentation

• PRBC transfusions

• High-potassium foods, drugs, nutritional supplements

Extracellular shifts (movement of potassium out of cells)

• Acidosis

• Hemolysis, tumor lysis, rhabdomyolysis (e.g., burn injury)

• Hypoinsulinemia, diabetic ketoacidosis

• β-blockers

Artifact

• Hemolysis

  • Capillary stick (finger/heel stick) technique

  • Specimen sitting for too long before testing

  • Shaking test tube, transporting in pneumatic tube

• Usually asymptomatic

• Muscle weakness, paralysis

• EKG changes

  • Shortened QT interval

  • Widened PR interval

  • Widened QRS

• Cardiac arrhythmia (ventricular fibrillation, asystole)

• Ensure quality specimen (ideally venipuncture)

• EKG to evaluate for electrocardiographic changes

• Transtubular potassium gradient (TTKG) if concern for kidney potassium retention

  • Should be >7 if hyperkalemic; low value suggests hypoaldosteronism

• Treat underlying cause

• Stabilize:

  • Calcium

  • Insulin + glucose: shift potassium intracellularly by stimulating Na⁺/K⁺-ATPase

  • β-agonists (e.g., albuterol, epinephrine): shift potassium intracellularly by stimulating Na⁺/K⁺-ATPase

  • Sodium bicarbonate (NaHCO₃): stimulates release of H⁺ from cells in exchange for K⁺ via H⁺-K⁺ exchanger to maintain electroneutrality

• Remove excess potassium (definitive therapy):

  • Diuretics

    • Thiazide diuretics

    • Loop diuretics

  • Sodium polystyrene sulfonate (SPS, Kayexalate®)

    • Ion exchange resin - exchanges Na⁺ for K⁺

      • Large sodium load, can cause hypernatremia

      • In vivo, 1 g of SPS delivers ~33 mg (1.4 mEq) Na⁺ and binds ~1 mEq of K⁺

        • In vitro, 1 g SPS contains ~100 mg (4.1 mEq) Na and will bind 2-3.1 mEq K

    • Given orally or rectally

      • Risk of bowel obstruction, perforation or necrosis

  • Dialysis

    • Treatment of choice for severe, life-threatening hyperkalemia