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Source: Brophy DF, Frumin J. Disorders of Potassium and Magnesium Homeostasis. In: DiPiro, JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM. Pharmacotherapy: A Pathophysiologic Approach. 8th ed. Accessed August 20, 2012.

  • Serum potassium <3.5 mEq/L (<3.5 mmol/L)
    • Mild: serum potassium 3.1–3.5 mEq/L (3.1–3.5 mmol/L)
    • Moderate: serum potassium 2.5–3.0 mEq/L (2.5–3.0 mmol/L)
    • Severe: serum potassium <2.5 mEq/L (<2.5 mmol/L)

Table 1. Mechanism of Drug-Induced Hypokalemia

  • Results from total body potassium deficit or shifting of serum potassium into intracellular compartment.
  • Thiazide and loop diuretics inhibit renal sodium reabsorption, resulting in increased sodium at distal tubule selectively reabsorbed as potassium excreted.
    • Volume contraction with diuretics stimulates secretion of aldosterone that promotes renal excretion of potassium.
  • Diarrhea and/or vomiting promote excessive loss of potassium-rich gastrointestinal (GI) fluid.
  • Hypomagnesemia reduces intracellular potassium concentration and promotes renal wasting, contributing to development of hypokalemia.

  • Commonly encountered electrolyte abnormality in clinical practice
  • Nonexistent in healthy adults

  • Eat potassium-rich diet:
    • Fresh fruits
    • Vegetables
    • Fruit juices
    • Meats
  • Patients on thiazide or loop diuretics should consider oral potassium supplementation.

  • Age: more common in elderly patients with chronic disease
  • Nasogastric suctioning
  • Use of thiazide or loop diuretics

  • Signs and symptoms nonspecific and variable, and depend on degree of hypokalemia and rapidity of onset.

Signs and Symptoms

  • Mild hypokalemia (serum potassium 3.1–3.5 mEq/L [3.1–3.5 mmol/L])
    • Often asymptomatic
  • Moderate hypokalemia (serum potassium 2.5–3.0 mEq/L [2.5–3.0 mmol/L])
    • Muscle cramps
    • Muscle weakness
    • Malaise
    • Myalgias
  • Severe hypokalemia (serum potassium <2.5 mEq/L [<2.5 mmol/L])
    • Cardiovascular
      • Electrocardiogram (ECG) changes include:
        • ST-segment depression or flattening
        • T-wave inversion
        • U-wave elevation
      • Clinical arrhythmias
        • Heart block
        • Atrial flutter
        • Paroxysmal atrial tachycardia
        • Ventricular fibrillation
        • Digitalis-induced arrhythmias
    • Musculoskeletal
      • Cramping and impaired muscle contraction

Means of Confirmation and Diagnosis

  • Serum potassium <3.5 mEq/L (<3.5 mmol/L)

Laboratory Tests

  • Metabolic panel
    • Serum potassium
    • Serum magnesium
    • Serum creatinine
  • Urinalysis
    • Urine potassium establishes pathophysiologic mechanism.

Diagnostic Procedures

  • ECG

Differential Diagnosis

  • Prevent development.
  • Treat serious life-threatening complication.
  • Normalize serum potassium concentration.
  • Prevent overcorrection of serum potassium concentration.

  • If hypomagnesemia is also present, correct magnesium deficiency first to ensure full repletion of potassium deficit.

  • Mild hypokalemia
    • Encourage ...

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