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Snapshot
  • HyperK-ECGA 26-year-old woman has just finished running a full marathon. She did not stop as often as she would have liked for water to rehydrate during her 26.2 mile run. She reports feeling lightheaded and has mild muscle soreness. When she went to use the restroom, she noticed that her urine was dark – almost like tea. At an urgent care clinic, her serum creatine kinase is found to be elevated. An ECG is shown here.
Introduction
  • Clinical definition
    • skeletal muscle breakdown and necrosis
      • releases intracellular contents of the cells into circulation
      • causes severe complications including acute kidney injury, compartment syndrome, cardiac arrest, or respiratory failure
  • Epidemiology
    • risk factors
      • intense physical exercise under heat or humidity
      • diuretic abuse
      • marathon running
  • Etiology
    • trauma
    • crush injury
    • alcohol abuse
    • cocaine abuse
    • statins and fibrates together
    • neuroleptic malignant syndrome
  • Pathogenesis
    • mechanism
      • muscle cell injury causes intracellular contents to be released including:
        • potassium
        • myoglobin
        • uric acid
        • sarcoplasmic contents
          • creatine kinase
          • alanine aminotransferase (ALT)
          • aspartate aminotransferase (AST)
    • cocaine-induced rhabdomyolysis
      • prolonged vasoconstriction can lead to ischemia and necrosis of muscle cells
    • acute kidney injury
      • high levels of myoglobin precipitates in kidneys and cause tubular obstruction
      • metabolites of myoglobin also directly causes damage to tubules
  • Prognosis
    • generally good with early detection, supportive care, and careful monitoring
Presentation
  • Symptoms
    • primary symptoms
      • classic triad
        • muscle pain
        • weakness and swelling of muscle
        • tea-colored urine (myoglobinuria)
    • nausea
    • emesis
    • oliguria or anuria
    • may be asymptomatic
  • Physical exam
    • fever
    • tachycardia
    • muscle weakness
Studies
  • Labs
    • ↑ serum creatine kinase (CK)
    • ↑ serum myoglobin
      • because of its short half-life they are not as sensitive as CK
    • ↑ serum creatinine
    • electrolyte abnormalities
      • ↑ potassium
      • ↑ phosphate
      • ↓ calcium
      • ↑ uric acid
    • ↑ liver function tests
  • Urine dipstick
    • myoglobinuria
  • Urinalysis
    • protein
    • brown casts
    • uric acid crystals
    • red blood cells
  • Electrocardiogram (ECG)
    • monitor for cardiac arrhythmias from electrolyte abnormalities
    • first step in evaluating a patient with suspected rhabdomyolysis
  • Diagnostic criteria
    • elevated serum CK
Differential
  • Hemolysis causing hemoglobinuria (dark urine)
    • normal CK
Treatment
  • Conservative 
    • fluid hydration and mannitol 
      • indications
        • for all patients to help treat or prevent acute kidney injury
  • Medical
    • sodium bicarbonate
      • indications
        • to alkalinize the urine
    • insulin and glucose
      • indications
        • if rhabdomyolysis causes hyperkalemia
Complications
  • Acute kidney injury
  • Cardiac arrest from hyperkalemia

 

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