Rhabdomyolysis

Definition

Rhabdomyolysis is the breakdown of muscle fibers resulting in the release of muscle fiber contents into the circulation. Some of these are toxic to the kidney and frequenty result in kidney damage.

Causes, incidence, and risk factors

Myoglobin is an oxygen-binding protein pigment found in the skeletal muscle. When the skeletal muscle is damaged, the myoglobin is released into the bloodstream. It is filtered out of the bloodstream by the kidneys. Myoglobin may occlude the structures of the kidney, causing damage such as acute tubular necrosis or kidney failure.

Myoglobin breaks down into potentially toxic compounds, which will also cause kidney failure. Necrotic (dead tissue) skeletal muscle may cause massive fluid shifts from the bloodstream into the muscle, reducing the relative fluid volume of the body and leading to shock and reduced blood flow to the kidneys.

The disorder may be caused by any condition that results in damage to skeletal muscle, especially trauma.

Risk factors include the following:

• Severe exertion such as marathon running or calisthenics
  
• Ischemia or necrosis of the muscles (as may occur with arterial occlusion, Deep venous thrombosis, or other conditions)
  
• Seizures
  
• Use or overdose of drugs-especially cocaine, amphetamines, statins, heroin, or PCP
  
• Trauma
  
• Shaking chills
  
• Heat intolerance and/or heatstroke
  
• Alcoholism (with subsequent muscle tremors)
  
• Low phosphate levels
  

Symptoms

• Abnormal urine color (dark, red, or cola colored)
  
• Muscle tenderness
  
• Weakness of the affected muscle(s)
  
• Generalized weakness
  
• Muscle stiffness or aching (myalgia)
  

Additional symptoms that may be associated with this disease include the following:

• Weight gain (unintentional)
  
• Seizures
  
• Joint pain