Rhabdomyolysis

Descriptive text is not available for this image BASICS

DESCRIPTION

  • Breakdown of muscle and release of intracellular contents into the bloodstream
  • Most commonly caused by traumatic muscle injury
  • Typically presents with muscle pain, weakness, and reddish-brown (tea-colored) urine
  • Up to 50% of patients are asymptomatic.

EPIDEMIOLOGY

Most common among

  • Males; <10 years old; >60 years old; BMI >40 kg/m2
  • Most commonly cited causes in adults are trauma and drugs. In pediatric cases, up to 1/3 can be due to infection (1)[A].

Incidence

  • 25,000 reported cases annually in the United States (1)[A]
  • Although muscle-related side effects of statins are the most common reason for discontinuation of statins, rhabdomyolysis is rare (0.5% of patients)

Prevalence

  • The prevalence of acute kidney injury (AKI) is 5 to 30% with rhabdomyolysis, which contributes significantly to morbidity and mortality (1)[A]
  • Without AKI, mortality is 20%; with AKI, mortality increases up to 50%

ETIOLOGY AND PATHOPHYSIOLOGY

  • Direct muscle trauma (most common cause)
    • Crush injuries; fractures; extended periods of muscle pressure (during surgery, unconscious from alcohol ingestion, coma); burns, electrocution, lightning strike
  • Muscle exertion
    • New strenuous and/or prolonged physical exercise (marathon runners, athletes, contact sports); seizures; delirium tremens; malignant hyperthermia; neuroleptic malignant syndrome (NMS)
  • Drugs and toxins
    • Alcohol; cocaine (most common recreational drug), phencyclidine, heroin, bath salts, and synthetic marijuana has been associated with severe rhabdomyolysis.
    • Antipsychotics (due to NMS, malignant hyperthermia, and dystonia)
    • Antimalarials
    • HMG-CoA reductase inhibitors (statins)—develops about 2 to 3 weeks after initiating therapy (risk <0.01%, elevated with higher doses and in combination with fibrates) (1)[A]
    • Corticosteroids
    • Toxins: carbon monoxide, snake envenomation, scorpion bites
  • Muscle ischemia
    • Thrombosis, embolism, sickle cell disease, compartment syndrome, tourniquets
  • Infections
    • Viral: influenza A and B, coxsackievirus, HIV, varicella
    • Bacterial: Streptococcus or Staphylococcus sepsis, Salmonella, Legionella
    • Parasite: malaria
  • Hypothermia; hyperthermia.
  • Autoimmune disorders
    • Polymyositis, dermatomyositis
  • Metabolic and endocrinologic:
    • Hypothyroidism or thyrotoxicosis; electrolyte imbalances (e.g., hyponatremia, hypernatremia, hypokalemia, hypocalcemia, hypophosphatemia); hyperosmolar state

Genetics

Hereditary causes of rhabdomyolysis are rare but should be suspected in children, patients with recurrent attacks, or patients who have attacks after minimal exertion, mild illness, or starvation.

  • Genetic disorders
    • Muscular dystrophies; disorders of lipid metabolism (e.g., carnitine palmitoyltransferase deficiency)
    • Disorders of carbohydrate metabolism (i.e., phosphofructokinase deficiency); glycogen storage diseases (e.g., phosphorylase B kinase deficiency) and others (e.g., lactate dehydrogenase A deficiency)
    • Mitochondrial disorders

RISK FACTORS

  • Bodyweight more than 30% above ideal body weight
  • Immobilization/compression for 6 hours or more
  • Extracellular volume loss
  • Pre-existing azotemia
  • Diabetes
  • Hypertension

GENERAL PREVENTION

  • Avoid excessive exertion; ensure adequate hydration.
  • Avoid precipitating drugs, metabolic and electrolyte abnormalities.

COMMONLY ASSOCIATED CONDITIONS

  • AKI
  • Disseminated intravascular coagulation (DIC)
  • Compartment syndrome

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