Rhabdomyolysis is a syndrome characterized by muscle necrosis and the release of intracellular muscle constituents into the circulation. Creatine kinase levels are typically markedly elevated, and muscle pain and myoglobinuria may be present. The severity of illness ranges from asymptomatic elevations in serum muscle enzymes to life-threatening disease associated with extreme enzyme elevations, electrolyte imbalances, and acute kidney injury.
The clinical manifestations and diagnosis of rhabdomyolysis will be reviewed here. The causes of rhabdomyolysis; the clinical features and diagnosis of acute kidney injury due to rhabdomyolysis; the management of patients with rhabdomyolysis, including methods to prevent acute kidney injury and related metabolic complications; and the prevention and management of acute compartment syndrome are discussed in detail separately. (See "Clinical features and diagnosis of heme pigment-induced acute kidney injury (acute renal failure)" and "Prevention and treatment of heme pigment-induced acute kidney injury (acute renal failure)" and "Crush-related acute kidney injury (acute renal failure)" and "Acute compartment syndrome of the extremities".)
Rhabdomyolysis is characterized clinically by myalgias, red to brown urine due to myoglobinuria, and elevated serum muscle enzymes (including creatine kinase) . The degree of muscle pain and other symptoms varies widely. Rhabdomyolysis associated with viral infection is discussed in further detail separately. (See "Viral myositis", section on 'Viral myositis with rhabdomyolysis'.)
Symptoms — The characteristic triad of complaints in rhabdomyolysis is muscle pain, weakness, and dark urine [2-5]. However, more than half of patients may not report muscular symptoms ; in contrast, occasional others may experience very severe pain. Muscle pain, when present, is typically most prominent in proximal muscle groups, such as the thighs and shoulders, and in the lower back and calves [2,5]. Other muscle symptoms include stiffness and cramping.
Additional symptoms that are more common in severely affected patients include malaise, fever, tachycardia, nausea and vomiting, and abdominal pain . Altered mental status may occur from the underlying etiology (eg, toxins, drugs, trauma, or electrolyte abnormalities).