Myalgias and Myopathies: Rhabdomyolysis

Rhabdomyolysis is the rapid breakdown of skeletal muscle with release of electrolytes, myoglobin, and other proteins into the circulation. The clinical presentation encompasses a spectrum of patients ranging from those with asymptomatic increases in creatine kinase (CK) levels to those with fulminant disease complicated by acute kidney injury (AKI), severe electrolyte abnormalities, compartment syndrome, and disseminated intravascular coagulation. A CK level at least 10 times the upper limit of normal typically is considered diagnostic, as is myoglobinuria. AKI is the most significant complication. Prompt recognition and management of rhabdomyolysis is crucial to preserving renal function. Management consists of rapidly initiating aggressive intravenous saline resuscitation to maintain a urine output of at least 300 mL/hour. Sodium bicarbonate can be used for patients who are acidotic, and mannitol can be used for those whose urine output is not at goal. Significant electrolyte abnormalities may be present and must be managed to avoid cardiac arrhythmias and arrest. Compartment syndrome can develop as an early or late finding and requires decompressive fasciotomy for definitive management. Intravenous fluids typically are continued until CK levels are lower than 1,000 U/L.