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Peter Thorne and Patrick Steadman


  • Potassium (K+) \< 3.5 mEq/L

  • 98% of total body K+ is intracellular (majority in muscle cells)

  • Goal: prevent life threatening complication (e.g. arrhythmia), replace deficit, elucidate cause

  • Insulin and catecholamines (Beta adrenoreceptors) are key drivers of transcellular shifts

  • H+ and K+ will trade places to maintain electroneutrality


  • Malaise, weakness, myalgias, decreased gastrointestinal motility

  • EKG changes:

    • Mild: ST segment depression, decreased T wave amplitude

    • Severe: U-waves (most commonly seen in precordial leads V2 and V3)

  • Severe hypokalemia can lead to rhabdomyolysis


  • History: decreased K+ intake, increased entry into cells (ex: elevated beta-adrenergic activity, hypothermia), GI losses, urinary losses (diuretics, hypomagnesemia, RTA, tubular defects, hyperaldosteronism)

  • If concomitant metabolic alkalosis: Normal/low BP suggests diuretic use, vomiting or Gitelman/Bartter syndromes

  • Hypertension suggests renovascular disease or primary mineralocorticoid excess

  • Labs: BMP, CBC, VBG, urine electrolytes, magnesium, POC glucose, CK. Possibly aldosterone, renin, cortisol pending clinical context

  • Imaging: Renal US, CT AP


  • Check Mg+2, replete to 2; Give empirically while waiting for serum Mg+2

  • K+ preparation (route); replete to 4

  • Choice of agent:

    • KCl is used for repletion in the hospital

      • PO tablets for mild asymptomatic hypokalemia

      • IV can be given through peripheral (rate is 10mEq/hr, may have burning sensation) or central access

    • K+ bicarbonate can be dissolved and put through G tube

      • Useful in pts with hypokalemia and metabolic acidosis
  • Dose:

    • Normal renal function: 10 mEq K+ is expected to raise serum [K+] by 0.1 mEq/L

    • Significant CKD or AKI: at risk of overcorrection

      • Shortcut: multiply the mEq by the Cr = how much K+ expected to rise

      • Once K+ higher than 5.5, K+ increases much faster and rules above do not apply