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Rhabdomyolysis is the breakdown of muscle fibers resulting in the release of muscle fiber contents (myoglobin) into the bloodstream. Some of these are harmful to the kidney and frequently result in kidney damage.

When muscle is damaged, a protein pigment called myoglobin is released into the bloodstream and filtered out of the body by the kidneys. Myoglobin breaks down into potentially harmful compounds. It may block the structures of the kidney, causing damage such as acute tubular necrosis or kidney failure.

Dead muscle tissue may cause a large amount of fluid to move from the blood into the muscle, reducing the 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:

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

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

• Fatigue
• Joint pain
• Seizures
• Weight gain (unintentional)

An examination reveals tender or damaged skeletal muscles.

• CPK is very high.
• Serum myoglobin test is positive.
• Serum potassium may be very high
• Urinalysis may reveal casts and be positive for hemoglobin without evidence of red blood cells on microscopic examination.
• Urine myoglobin test is positive.

This disease may also alter the results of the following tests:

• CPK isoenzymes
• Urine creatinine
• Serum creatinine

The outcome varies depending on the extent of kidney damage.

• Acute tubular necrosis
• Acute renal failure

Call your health care provider if symptoms indicate rhabdomyolysis may be present.

Drink plenty of fluids after strenous exercise to dilute the urine and flush the myoglobin out of the kidney. Proper hydration is also necessary after any condition or event that may involve damage to skeletal muscle.