Hypokalemia

Basics

Description

  • Hypokalemia: Serum potassium <3.5 mEq/L:
    • Mild: 3–3.4 mEq/L
    • Moderate: 2.5–3.0 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

Increased Intracellular Uptake

  • Insulin administration
  • Inhalation of β-adrenergic agent such as albuterol

Poor Intake (Rare As A Sole Cause)

  • <1 g of potassium per day
  • Chronic malnourishment
  • Alcoholism

Sweat

  • 5% daily

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