Rhabdomyolysis

Rhabdomyolysis causes weakness and muscle pain.

Rhabdomyolysis describes the condition where striated skeletal muscle cells break down and the cell contents spill into the bloodstream. It can cause problems with electrolyte abnormalities, dehydration, acid-base balance of the body, heart rhythm disturbances, and kidney damage.

There are three types of muscle in the body:

• Smooth muscles are a type of muscle that contract without voluntary control and are under the control of the autonomic nervous system. They line tubular structures in the body such as the stomach and intestine, blood vessels, and the bladder. They help regulate function of these tubular structures.
• Cardiac or heart muscle
• Striated muscle is attached to the skeleton and allows the body to move.

Rhabdomyolysis is the definition of damage to striated muscles:

• Rhabdo = striped, striated
• Myo = muscle
• Lysis = cell disintegration because of damage to the cell wall

What is the most common cause of rhabdomyolysis?

The most common causes of rhabdomyolysis include trauma, direct muscle injury, and extreme, prolonged exertion or exercise.

In trauma, muscles can be injured directly, or they can be damaged when their blood supply is interrupted. Traumatic events can include prolonged immobility when a victim is trapped, crush injuries, severe burns, and high voltage electrical injuries.

Rhabdomyolysis can occur with strenuous and prolonged exercise, especially when the body is unaccustomed to the activity or has not trained adequately. Muscle damage may occur in people who start new exercise programs and begin with intense workouts, instead of gradually increasing the amount and length of the activity.

Rhabdomyolysis may occur when exertion happens in high heat and humidity, and also when the body is unable to cool itself because of restrictive clothing or uniform or due to some medications that limit the ability of the body to sweat.

Other medical emergencies that cause muscles to contract for extended periods of time include prolonged seizures, delirium tremens, and amphetamine overdose.

Some non-trauma causes of rhabdomyolysis include medications, poisonings, drug abuse, electrolyte abnormalities, infections, genetic muscle abnormalities, and severe endocrine diseases such as diabetes and thyroid disorders.

Can dehydration cause rhabdomyolysis?

Dehydration is not a cause of rhabdomyolysis, but dehydration can worsen the complications when muscle damage does occur. Dehydration decreases the ability of the body to adjust to high levels of myoglobin and potassium released from muscle cells, and increases the potential complications of kidney failure and heart rhythm disturbances.

What are the warning signs and red flags of rhabdomyolysis?

The classic triad of symptoms of rhabdomyolysis include:

• Muscle pain. Pain usually involves the large muscles of the body including the thighs and shoulders. There also may be noticeable muscle swelling.
• Weakness. Muscles that are painful may also be weak.
• Brownish red urine. Damaged muscle cells release myoglobin into the bloodstream and this is filtered into the urine by the kidneys, giving the appearance of tea-colored or cola-colored urine.

Other symptoms may include nausea, vomiting, malaise, and exhaustion.

In mild circumstances, rhabdomyolysis may have no symptoms.

How long after exercise can rhabdomyolysis occur?

The symptoms of rhabdomyolysis may appear almost immediately with muscle pain and swelling, or they may be delayed by hours and days, and the diagnosis only considered when there is a change in urine color.

The diagnosis should be considered when a patient presents with dark-colored urine, muscle pain and swelling, and there is history of trauma or extreme exercise. It is a harder diagnosis to make if the cause of rhabdomyolysis is not trauma, but one of the many other causes like medications side effect, seizure, hypothyroidism, or drug abuse.

The healthcare provider will need to take a careful history to understand the potential cause. This will include reviewing past medical history, medication history, and social factors like alcohol and drug use.

Blood tests and urine samples will help confirm the diagnosis.

Creatine phosphokinase (CPK) will be markedly elevated. There are other muscle markers that are elevated in the blood, but CPK is most accurate. There are two types of CPK that can be measured. CPK-MM is found in skeletal muscle. CPK-MB is found in heart muscle.

In rhabdomyolysis, it is the CPK-MM that is elevated.

Urinalysis consistent with myoglobin in the urine. A dipstick test will be positive for blood in the urine, but looking at the urine under a microscope reveals no red blood cells. This presumes that the positive dipstick test is due to myoglobin.

Treatment of rhabdomyolysis is supportive. Intravenous fluids are used to keep the body well-hydrated and to minimize the risk of kidney injury.

If the cause is nontraumatic, then the underlying disease needs to be treated to prevent ongoing muscle damage.

Being aware of the potential complications like electrolyte abnormalities, compartment syndrome, and others, allows the health care team to prepare for issues should they arise.

Can rhabdomyolysis go away on its own?

In cases of mild rhabdomyolysis, without evidence of complications, treatment is supportive and oral rehydration may be all that is needed.

In more severe cases, hospitalization may be required for both treatment and monitoring.

Continuing muscle damage stops when the underlying cause is diagnosed and addressed. This may be stopping activities, addressing electrolyte abnormalities, or discontinuing offending medications.

What organs can be damaged from rhabdomyolysis?

The most significant complications of rhabdomyolysis are acute kidney injury and heart rhythm disturbances.

When myoglobin is release from damaged muscle cells into the bloodstream, it is filtered by the kidneys. Inside the kidneys, the myoglobin molecule is sometimes too big to fit through the filtering system and it can clog those tubules. Kidney injury may occur and waste products of metabolism cannot be processed by the damaged kidney and kidney failure may occur.

When rhabdomyolysis is diagnosed, one of the mainstays of treatment is intravenous rehydration to increase urine flow and reduce the risk of kidney damage. Medications may also be used to maximize urine production.

Muscle cells that are damaged can also leak potassium into the blood stream. Hyperkalemia, elevated potassium, potentially changes the electrical condition in heart muscle and may cause life-threatening heart rhythm disturbances like ventricular tachycardia and ventricular fibrillation.

Other complications seen with rhabdomyolysis include compartment syndrome and disseminated intravascular coagulation (DIC).

Most often, patients recover completely from rhabdomyolysis. The prognosis is usually favorable with prompt diagnosis and treatment.

Rhabdomyolysis associated with kidney damage and electrolyte imbalance may require hospitalization. Even in these cases, recovery is expected.

Prevention is possible for those who develop rhabdomyolysis from excessive exertion.

Planning exercise and work activity to gradually increase to strenuous levels will allow the body to acclimate to the work load and minimize the risk of muscle damage. Listening to your body and appreciating excess muscle stress and fatigue is important. Minimizing heat exposure, wearing appropriate clothing, and maximizing hydration are appropriate well-being strategies.

Rhabdomyolysis may be a complication of some medications and illnesses. It is important to listen and learn from your health care provider, to ask questions about new medications, and to report any concerning symptoms immediately.

• Rhabdomyolysis describes muscle cell damage most often due to trauma, or excessive, strenuous, and prolonged exercise. Chemicals like myoglobin and potassium leak into the blood stream causing potential organ damage.
• The classic triad of rhabdomyolysis symptoms include: muscle pain, muscle weakness, and dark-colored urine.
• Elevated levels of the muscle enzyme CPK helps confirm the diagnosis. Urine myoglobin also helps with confirmation.
• Hydration is the primary treatment. Intravenous fluids may be needed.
• Hospitalization is sometimes required to treat the complications of rhabdomyolysis, including kidney injury and heart rhythm disturbances.