Hypokalemia

Hypokalemia is a topic covered in the 5-Minute Emergency Consult.

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Basics

Description

  • Hypokalemia: Serum potassium <3.5 mEq/L:
    • Mild: 3–3.5 mEq/L
    • Moderate: 2.5–2.9 mEq/L
    • Severe: <2.5 mEq/L
  • 98% of total body potassium is found intracellularly
  • Cellular potassium gradient is maintained by Ns-K ATPase
  • Functions of intra- and extracellular potassium gradient:
    • Resting cell membrane potential
    • Cardiac activity
    • Muscle and nerve activity

Etiology

Renal Losses
  • Most common site of potassium loss
  • Medications: Diuretics, penicillin and its derivatives, cisplatin
  • Hyperaldosteronism
  • Genetic disorders: Bartter syndrome and Gitelman syndrome

GI Losses
  • Drainage from NG tube
  • Increased ostomy output
  • Vomiting/diarrhea

Poor Intake (Rare as a Sole Cause)
  • <1 g of potassium per day
  • Chronic malnourishment
  • Alcoholism

Sweat
5% daily

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Basics

Description

  • Hypokalemia: Serum potassium <3.5 mEq/L:
    • Mild: 3–3.5 mEq/L
    • Moderate: 2.5–2.9 mEq/L
    • Severe: <2.5 mEq/L
  • 98% of total body potassium is found intracellularly
  • Cellular potassium gradient is maintained by Ns-K ATPase
  • Functions of intra- and extracellular potassium gradient:
    • Resting cell membrane potential
    • Cardiac activity
    • Muscle and nerve activity

Etiology

Renal Losses
  • Most common site of potassium loss
  • Medications: Diuretics, penicillin and its derivatives, cisplatin
  • Hyperaldosteronism
  • Genetic disorders: Bartter syndrome and Gitelman syndrome

GI Losses
  • Drainage from NG tube
  • Increased ostomy output
  • Vomiting/diarrhea

Poor Intake (Rare as a Sole Cause)
  • <1 g of potassium per day
  • Chronic malnourishment
  • Alcoholism

Sweat
5% daily

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