Rhabdomyolysis


 

Causes

Most common causes in adults include:

  • Alcohol and drug abuse
  • Toxin ingestion
  • Trauma (typically crush injury)
  • Infection (most frequently Legionella)
  • Prolonged immobility
  • Heat-related injury
  • Strenuous physical activity (especially when poorly conditioned, older age, excessive heat/humidity, or inadequate fluid intake)
  • Myoglobin (released from dying muscle) has a toxic effect on the kidneys and may cause renal failure in extreme cases.
Other Causes
Trauma  Immunologic diseases involving muscle  Ischemic injury 
  Crush injury   Dermatomyositis   Compartment syndrome
  Electrical or lightning injury   Polymyositis   Compression
Drugs of abuse  Bacterial infection  Medications 
  Amphetamines [including Ecstasy (3,4-methylenedioxymethamphetamine)]   Clostridium    Antipsychotics
  Group A -hemolytic streptococci   Barbiturates
  Caffeine   Legionella    Benzodiazepines
  Cocaine   Salmonella     Clofibrate
  Ethanol   Shigella     Colchicine
  Heroin   Staphylococcus aureus    Corticosteroids
  Lysergic acid diethylamide   Streptococcus pneumoniae    Isoniazid
  Methamphetamines Viral infection    Lithium
  Opiates   Coxsackievirus   Monoamine oxidase inhibitors
  Phencyclidine   Cytomegalovirus   Narcotics
Environment and excessive muscular activity    Epstein-Barr virus   Neuroleptic agents
  Contact sports   Enterovirus   Phenothiazines
  Delirium tremens   Hepatitis virus   Salicylates
  Dystonia   Herpes simplex virus   Selective serotonin reuptake inhibitors
  Psychosis   Human immunodeficiency virus   Statins
  Seizures   Influenza virus (A and B)   Theophylline
  Sports and basic training   Rotavirus   Tricyclic antidepressants
  Heat stroke       Zidovudine
Genetic disorders         
  Glycolysis and glycogenolysis disorders      
  Fatty acid oxidation disorders      
  Mitochondrial and respiratory chain metabolism disorders      
 

Symptoms/Exam

  • Myalgias
  • Weakness
  • Fever
  • Dark/brown urine
  • Occasional altered mental status (urea-induced encephalopathy)
 

Diagnosis

  • Elevated Creatine Phosphokinase (>5 times normal) is the most sensitive marker.
  • Myoglobinuria is pathognomonic, but is rapidly cleared.
  • UA with blood on urine dipstick, but minimal RBCs on microscopic evaluation
  • Electrolyte abnormalities include hypocalcemia (most common), hyperphosphatemia, hyperkalemia.
 

Treatment and Disposition

  • Mainstay of therapy is aggressive hydration with crystalloid that does not contain potassium.
    • Curry and colleagues recommended rapid correction of the fluid deficit with IV crystalloids followed by infusion of 2.5 mL/kg/h, with the goal of maintaining a minimum urine output of 2 mL/kg/h.
    • Others recommend a goal of 200 to 300 mL of urine output each hour
  • IV Bicarbonate to urine pH > 6.5 to enhance renal myoglobin clearance (uncertain benefit)
    • 1 ampule (44 mEq) added to 1 L of half NS
      OR
    • 2-3 ampules (88 to 132 mEq) to 5% dextrose in water to run at 100 mL/h
  • Consider mannitol to maintain urine output.
    • One protocol recommends 20% mannitol administered as 1 gram/kg IV over 30 minutes 
      OR
    • 25 grams IV initially, followed by 5 grams/h IV, for a total of 120 grams/d.
    • Mannitol administration can worsen dehydration and oliguria
  • All cases require admission to follow and treat metabolic abnormalities.
  • Urinary Cath. for all critical pts
  • Hypocalcemia
    • Observed early in rhabdomyolysis usually requires no treatment.
    • Calcium should be given only to treat hyperkalemia-induced cardiotoxicity or profound signs and symptoms of hypocalcemia.
    • If hypercalcemia is symptomatic, saline diuresis should be continued.
  • Hyperphosphatemia
    • Should be treated with oral phosphate binders when serum levels are >7 milligrams/dL.
      • Calcium Acetate (Eliphos, PhosLo, Phoslyra)
      • Renvela (Sevelamer)
      • Fosrenol (Lanthanum)
      • Amphojel (Aluminum Hydroxide)
      • Velphoro (Sucroferric oxyhydroxide)
    • Hypophosphatemia should be treated when the serum level is <1 milligram/dL.
  • Hyperkalemia
    • Which is usually most severe in the first 12 to 36 hrs after muscle injury, can be significant and prolonged.
    • Traditional insulin and glucose therapy, although recommended, may not be as effective in rhabdomyolysis-induced hyperkalemia.
    • The use of ion-exchange resins (e.g., Kayexalate) is effective.
    • Dialysis may be needed
  • The use of prostaglandin inhibitors such as NSAIDs should be avoided because of their vasoconstrictive effects on the kidney. Most importantly, the underlying cause should be treated.
     
  • Disposition:
    • The majority of healthy patients with exertional rhabdomyolysis and without comorbidities (i.e., heat stress, dehydration, trauma) can usually be treated with oral or IV rehydration, observed in the ED, and then released.
    • Otherwise, patients should be admitted for IV hydration, diuresis, management of complications, and treatment of the underlying cause.
    • For at least the initial 24 to 48 hours, admission should be to a monitored bed to identify dysrhythmias.
    • The nephrology service should be consulted to evaluate the need for dialysis, especially for patients with hyperkalemia unresponsive to therapy
 

Complications

Acute renal failure
Metabolic derangements
  Hypercalcemia (late)
  Hyperkalemia
  Hyperphosphatemia
  Hyperuricemia
  Hypocalcemia
  Hypophosphatemia (late)
Disseminated intravascular coagulation
Mechanical complications
  Compartment syndrome
  Peripheral neuropathy
 
Cases in which you give IV Bicarbonate:
  • Rhabdomyolysis
  • Salicylate toxicity
  • (TCA) Tricyclic antidepressant toxicity
  • Hyperkalemia with acidosis
  • Severe acidosis

In rhabdomyolysis, hydration and alkalinization of urine (pH > 6.5) prevent renal failure by preventing precipitation of myoglobin in the urine.