Rhabdomyolysis

Rhabdomyolysis causes weakness and muscle pain.

• Rhabdomyolysis is the rapid destruction of skeletal muscle resulting in leakage into the urine of the muscle protein myoglobin.
• Rhabdomyolysis has many causes.
• Medications can cause muscle injury and rhabdomyolysis.
• Rhabdomyolysis can cause muscle pain and weakness.
• Blood levels of muscle enzymes, including CPK, SGOT, SGPT, and LDH, as well as blood and urine myoglobin are used to diagnose and monitor rhabdomyolysis.
• Hospitalization is sometimes required to treat rhabdomyolysis.

Rhabdomyolysis (RAB-DOE-MY-O-LIE-SIS) is the rapid destruction of skeletal muscle resulting in leakage into the urine of the muscle protein myoglobin.

There are three different types of muscle in the human body;

1. smooth muscle,
2. skeletal muscle, and
3. heart muscle.

The skeletal muscle is the muscle of movement of the body (moving the skeleton at the joints). Skeletal muscle is affected by rhabdomyolysis.

Myoglobin is a protein component of the muscle cells that is released into the blood when the skeletal muscle is destroyed in rhabdomyolysis. Creatine kinase is an enzyme (a protein that facilitates chemical reactions in the body) and also in the muscle cells. The level of each of these proteins can be measured in the blood to monitor the degree of muscle injury from rhabdomyolysis. Myoglobin can also be measured in samples of urine.

Rhabdomyolysis has many causes:

• Muscle trauma or crush injury
• Severe burns
• Physical torture or child abuse
• Prolonged lying down on the ground (people who fall or are unconscious and are unable to get up for several hours)
• Prolonged coma
• Severe muscle contractions from prolonged seizures
• Cocaine use with related hyperthermia (increased body temperature)
• Extreme physical activity (running a marathon, extreme workouts)
• Drug and alcohol intoxication
• Low circulating phosphate, potassium, or magnesium levels in the blood (electrolytes)
• Genetic muscle diseases (familial paroxysmal rhabdomyolysis)
• Prolonged drowning or hypothermia (low core body temperature)
• Medications: most notably statins used to treat high cholesterol (simvastatin [Zocor], atorvastatin [Lipitor], pravastatin [Pravachol], or lovastatin [Mevacor]) and other medications such as Parkinson's medication, psychiatric medications, anesthesia medications, HIV medications, colchicine
• Variety of viruses and some bacteria
• Severe hypothyroidism (low thyroid level), especially if the person is also taking statin drugs for cholesterol
• Lack of blood perfusion to a limb
• Some inflammatory disorders of the muscle, called myopathies, (myositis, dermatomyositis, polymyositis)
• Venom from certain snake bites (mainly in Africa, Asia, and South America)
• Haff disease

• Rhabdomyolysis may not cause any symptoms at all.
• Muscle aches and pain (myalgia), stiffness, and muscle weakness can occur with rhabdomyolysis and is especially common with severe muscle damage.
• Rhabdomyolysis may cause a darkening of the urine color.
• Myoglobin is released from the muscles when they break down and is excreted into the urine. This can cause a red or cola color in the urine.

If you have signs and symptoms suggestive of rhabdomyolysis, your doctor needs to be notified promptly. It is important to realize that these symptoms are not specific to rhabdomyolysis as they may be caused by other conditions.

Rhabdomyolysis is suggested by the history of recent and past events and the physical examination. It is confirmed by blood and urine testing. An important part of diagnosing rhabdomyolysis is a comprehensive medical history and physical examination.

• The medical history may include questions about any medication use, drug and alcohol use, other medical conditions, any trauma or accident, etc. Blood tests include a complete blood count (CBC), a metabolic panel, muscle enzymes, and urinalysis.
• The levels of myoglobin can be elevated in blood and urine
• The diagnosis of rhabdomyolysis is confirmed by detecting elevated muscle enzymes in the blood, which include creatine phosphokinase (CPK), SGOT, SGPT, and LDH. The levels of these enzymes rise as the muscle is destroyed in rhabdomyolysis.
• While the SGOT, SGPT, and LDH enzymes are found in muscles, they are more frequently associated with the liver. Therefore, elevations of SGOT and SGPT, without elevated CPK, are more typically indications of liver damage.

Of note, CPK is also in the heart muscle (cardiac muscle) and brain. The laboratory is usually able to distinguish between the different components of this enzyme. For example, the fraction coming from skeletal muscle is referred to as CK-MM and the one from heart muscle is designated as CK-MB. There are small amounts of the CK-MB component in the skeletal muscle as well.

• One of the dreaded complications of rhabdomyolysis is kidney failure. This can occur for a variety of reasons. Direct injury to the kidney and plugging of the filtering tubes of the kidneys by the muscle proteins are among the causes of kidney function impairment in the setting of rhabdomyolysis.
• Another serious complication of rhabdomyolysis is called compartment syndrome where muscle injury leads to swelling and increased pressure in a confined space (a compartment). This leads to compromised circulation which can endanger the affected tissue. The compartment syndrome is most common after injury in the lower leg, arms, or the muscles of the abdominal wall and can require emergency surgery.
• Rhabdomyolysis can also cause an abnormality of electrolytes in the blood. Because of muscle injury, the contents of the muscle cells can be released into the blood causing high levels of potassium (hyperkalemia) and phosphorus (hyperphosphatemia).

The treatment of rhabdomyolysis depends on its cause and severity.

If a cause for rhabdomyolysis is identified, it is addressed; for example:

• discontinuing a toxic medication,
• replacing electrolytes, or
• treating an underlying muscle disease.

In cases of mild rhabdomyolysis without any evidence of complications, management can take place at home by simply recognizing the cause and correcting it, such as discontinuing medication and rehydration.

In more severe cases, or if home therapy is not possible, hospitalization may be required. Prompt initiation of hydration with intravenous fluids, in addition to the removal of the provoking factor(s), is an essential part of the treatment of rhabdomyolysis. Monitoring and managing kidney dysfunction, correcting any disturbance in the electrolytes, and monitoring the muscle enzyme levels (CPK, SGOT, SGPT, LDH) are most effectively done in the hospital when rhabdomyolysis is severe.

• The overall prognosis of rhabdomyolysis is favorable as long as it is recognized and treated promptly.
• Most causes are rhabdomyolysis reversible.
• Severe cases of rhabdomyolysis may be associated with kidney damage and electrolyte imbalance and hospitalization and even dialysis can be required.