Rhabdomyolysis

• Muscle necrosis and release of intracellular constituents

Aetiology

Traumatic or compression

• Multiple trauma
• Crush injuries
• Vascular or orthopedic surgery
• Coma
• Immobilization

Nontraumatic

• Exertional
• Normal muscle
• Extreme exertion
• Environmental heat illness
• Sickle cell trait
• Seizures
• Hyperkinetic states
• Abnormal muscle
• Metabolic myopathies
• Mitochondrial myopathies
• Malignant hyperthermia
• Neuroleptic malignant syndrome
• Nonexertional
• Drugs and toxins

§ Alcohol

§ Anaesthetics

§ Illicit drugs

§ Snake venom

§ Petrol vapour

§ Statins

§ Fibrates

§ Neuroleptics

• Infections (including HIV)
• Electrolyte abnormalities
• Endocrinopathies (mild elevation with hypothyroidism)
• Inflammatory myopathies
• Miscellaneous

Clinical

• Myalgias (variable depending on cause)
• Red/brown urine (Myoglobinuria)
• Weakness rare unless late/severe disease
• Acute renal failure
• Due to haem casts
• Iron toxicity
• Most likely to occur when CK >5000-10000

Investigations

• CK raised
• Risk of ARF if >5000-10000
• Severe if >30,000
• AST/ALT also released from skeletal muscle breakdown
• Urine – pigmented casts, myoglobin
• Hyperkalaemia
• Hyperuricaemia (from release of purines from cells)
• Hypocalcaemia
• Hyperphosphataemia

Treatment

• Fluid administration
• Aim for urine output of 200-300ml/hr
• Forced Alkaline diuresis
• Some evidence that switching to a alkaline solution provides benefit
• Aim for urine pH >6.5
• Forced diuresis
• Some evidence that diuretics or mannitol provide benefit
• Monitor and correct electrolyte abnormalities
• Identify and treat cause (See Myopathies)