Rhabdomyolysis

Answer 1

Definition

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.

Causes, incidence, and risk factors

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)
• Certain inherited or genetic syndromes
• 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

Symptoms

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

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

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

Signs and tests

An examination reveals tender or damaged skeletal muscles.

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

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

• CPK isoenzymes
• Urine creatinine
• Serum creatinine

Treatment

Early and aggressive fluids (hydration) may prevent kidney damage by rapidly flushing myoglobin out of the kidneys. Fluids may need to be given through a vein (by IV). Some patients may need kidney dialysis.

Medicines that may be prescribed include diuretics and bicarbonate (if urine output is sufficient).

Hyperkalemia and low blood calcium levels (hypocalcemia) should be treated if present. Kidney failure should be treated as appropriate.

Expectations (prognosis)

The outcome varies depending on the extent of kidney damage. Acute kidney failure occurs in many patients. Treatment soon after rhabdomyolysis begins will reduce the risk of chronic kidney damage.

People with milder cases may return to normal activity within a few weeks to a month or more. However, some continue to have problems with fatigue and muscle pain.

Complications

• Acute tubular necrosis
• Acute renal failure

Calling your health care provider

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

Prevention

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.

References

In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 114.

Answer 2

Definition

Rhabdomyolysis is the breakdown of muscle fibers that leads to the release of muscle fiber contents (myoglobin) into the bloodstream. Myoglobin is harmful to the kidney and often causes kidney damage.

Causes, incidence, and risk factors

When muscle is damaged, a protein called myoglobin is released into the bloodstream. It is then filtered out of the body by the kidneys. Myoglobin breaks down into substances that can damage kidney cells.

Rhabdomyolysis may be caused by any condition that damages skeletal muscle, especially injury.

Risk factors include the following:

• Alcoholism(with muscle tremors)
• Crush injuries
• Drugs, especially cocaine, amphetamines, statins, heroin, or PCP
• Genetic muscle diseases
• Heatstroke
• Ischemia or necrosis of the muscles (which 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

Symptoms

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

Other symptoms that may occur with this disease:

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

Signs and tests

An examination shows tender or damaged skeletal muscles.

The following tests may be done:

• Creatine kinase(CK) level
• Serum calcium
• Serum myoglobin
• Serum potassium
• Urinalysis
• Urine myoglobintest

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

• CK isoenzymes
• Serum creatinine
• Urine creatinine

Treatment

Getting fluids that contain bicarbonate may prevent kidney damage by quickly flushing myoglobin out of the kidneys. Fluids may need to be given through a vein (by IV). Some patients may need kidney dialysis.

Medicines that may be prescribed include diuretics and bicarbonate (if there is enough urine output).

Hyperkalemia and low blood calcium levels (hypocalcemia) should be treated right away, if present. Kidney failure should also be treated.

Expectations (prognosis)

The outcome depends on the amount of kidney damage. Acute kidney failure occurs in many patients. Getting treated soon after rhabdomyolysis begins will reduce the risk of permanent kidney damage.

People with milder cases may return to their normal activities within a few weeks to a month. However, some people continue to have problems with fatigue and muscle pain.

Complications

• Acute tubular necrosis
• Acute renal failure
• Harmful chemical imbalances in the blood
• Shock (low blood pressure)

Calling your health care provider

Call your health care provider if you have symptoms of rhabdomyolysis.

Prevention

Drink plenty of fluids after strenuous exercise to dilute your urine and flush any myoglobin that is released from your muscles out of your kidneys. Also drink a lot of fluids after any condition or event that may have damaged skeletal muscle.

References

O'Connor FG, Deuster PA. Rhabdomyolysis. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 114.

Remuzzi G, Perico N, DeBroe ME. Acute kidney injury. In: Brenner BM, ed. Brenner and Rector's the Kidney. 8th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 29.

Reviewed By

Review Date: 09/19/2011

David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Herbert Y Lin, MD, PhD, Nephrologist, Massachusetts General Hospital; Associate Professor of Medicine, Harvard Medical School. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.