Rhabdomyolysis

Rhabdomyolysis

Definition:

A disorder involving injury to the kidney caused by toxic effects of the contents of muscle cells.

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:

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:

Signs and tests:

An examination reveals tender or damaged skeletal muscles.

A urinalysis may reveal casts and be positive for hemoglobin without evidence of red blood cells on microscopic examination.
A urine myoglobin test is positive.
A serum myoglobin test is positive.
A CPK is very high.
A serum potassium may be very high (potassium is released from cells into the bloodstream when there is cell breakdown).

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

Treatment:

Early and aggressive hydration may prevent complications by rapidly eliminating the myoglobin out of the kidneys. The hydration needs with muscle necrosis may approximate the massive fluid volume needs of a severely burned patient. This may involve intravenous administration of several liters of fluid until the condition stabilizes.

Diuretic medications such as mannitol or furosemide may aid in flushing the pigment out of the kidneys. If the urine output is sufficient, bicarbonate may be given to maintain an alkaline urine state. This helps to prevent the dissociation of myoglobin into toxic compounds.

Hyperkalemia should be treated if present. Kidney failure should be treated as appropriate.

Expectations (prognosis):

The outcome varies depending on the extent of kidney damage incurred.

Complications:

Calling your health care provider:

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

Prevention:

After any condition that may involve damage to skeletal muscle, hydration should be adequate to dilute the urine and flush the myoglobin out of the kidney. (See "Treatment".)

Review Date: 11/30/2001
Reviewed By: Andrew Koren, M.D., Department of Nephrology, NYU-Mount Sinai Medical Center, New York, NY. Review provided by VeriMed Healthcare Network.

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