Rhabdomyolysis, often referred to as “rhabdo,” is a serious condition that occurs when skeletal muscle tissue breaks down and releases its contents into the bloodstream. These substances, including muscle proteins like myoglobin, can cause severe damage to internal organs—especially the kidneys.

Skeletal muscles are the ones you control voluntarily for movement. When they are injured or destroyed, pain and swelling may occur, along with potentially dangerous chemical imbalances in the body. Around 25,000 cases of rhabdomyolysis occur each year in the United States, and while most people recover with early treatment, severe cases can lead to complications or even death.

Rhabdomyolysis Symptoms

Symptoms can range from mild discomfort to life-threatening complications. Some people may not show any signs at all, while others experience severe muscle and kidney damage.

Classic Symptoms

The three hallmark signs of rhabdomyolysis include:

  • Severe muscle pain or cramps, particularly in the calves or lower back

  • Weakness and fatigue, making it difficult to move or complete daily tasks

  • Dark-colored urine, resembling cola or tea, caused by myoglobin from muscle breakdown

Not everyone experiences all three symptoms, and some may only have one or two.

Symptoms From Electrolyte Abnormalities

Rhabdomyolysis can cause dangerous electrolyte imbalances due to the release of minerals from damaged muscle cells. Common abnormalities include:

  • High potassium (hyperkalemia)

  • High phosphorus (hyperphosphatemia)

  • Low calcium (hypocalcemia)

These changes may cause heart palpitations, seizures, muscle cramps, weakness, or spasms if left untreated.

Additional Symptoms

Other signs of rhabdomyolysis may include fever, rapid heartbeat, nausea, or vomiting. In more severe cases, symptoms may also reflect organ damage, particularly to the kidneys.

What Causes Rhabdomyolysis

Rhabdomyolysis can occur from various causes, ranging from physical trauma to medication use or genetic disorders.

Physical Trauma

Direct injury or crush syndrome is one of the most common causes. Severe trauma to muscles releases their contents into the bloodstream, triggering inflammation and systemic effects.

Strenuous Exercise

Overexertion can lead to rhabdomyolysis, especially if you start an intense workout program without allowing proper recovery. Heat and dehydration can worsen the risk.

Drugs

Certain medications and substances can also cause muscle breakdown, including:

  • Statin drugs (e.g., Lipitor or Crestor)

  • Non-statin cholesterol drugs (e.g., Zetia)

  • Psychiatric medications (e.g., Haldol, Prozac)

  • Allergy medications (e.g., Benadryl)

  • Alcohol and recreational drugs (e.g., cocaine, heroin)

Congenital Diseases

Some genetic disorders predispose individuals to rhabdomyolysis, such as:

  • Sickle cell disease

  • Muscular dystrophies

  • Mitochondrial diseases

  • Metabolic or enzyme deficiencies

Other Causes

Additional causes include:

  • Infections (flu, strep, salmonella, mononucleosis)

  • Electrolyte disorders

  • Heat stroke or hyperthermia

  • Prolonged immobility or unconsciousness

  • Dehydration

Often, multiple factors—like infection combined with dehydration—can act together to trigger rhabdomyolysis.

Diagnosis

Early diagnosis is critical to prevent complications. A healthcare provider will review your medical history, symptoms, and physical exam findings before ordering diagnostic tests.

Tests

The primary diagnostic test is the creatine phosphokinase (CPK) blood test, which measures muscle enzyme levels. High levels (five times above normal) strongly suggest rhabdomyolysis. Because CPK levels may fluctuate, testing may need to be repeated.

Additional tests include:

  • Blood tests: To check electrolytes, kidney function, and overall health.

  • Urine tests: To detect myoglobin in urine, confirming muscle breakdown.

  • Electrocardiogram (ECG): To monitor heart rhythm abnormalities from electrolyte imbalance.

  • Genetic testing: If no clear cause is identified.

Prompt testing and diagnosis can significantly improve outcomes.

Treatments For Rhabdomyolysis

Mild cases may resolve with rest and hydration, but severe cases require hospitalization.

IV Fluids: The cornerstone of treatment, intravenous fluids flush toxins and support kidney function.

Electrolyte Management: Blood levels are closely monitored and adjusted as needed to prevent heart or nerve complications.

Dialysis: In cases of kidney failure, dialysis may be used temporarily to remove waste from the blood.

Supportive Care: Patients with severe complications may need intensive care, including ventilator support.

Identifying and addressing the underlying cause—such as stopping a harmful medication—is essential to prevent recurrence.

Prevention

While not all cases are preventable, you can reduce your risk with proactive habits:

  • Gradually increase the intensity of your exercise routine

  • Take breaks during workouts, especially in hot environments

  • Stay well-hydrated and avoid excessive alcohol or caffeine

  • Stop physical activity immediately if you experience severe pain, weakness, or dark urine

  • Seek medical attention promptly if symptoms arise

Complications

Rhabdomyolysis can lead to serious health issues if untreated, especially when large amounts of muscle tissue are destroyed.

Acute Kidney Injury

Kidney damage is the most common and serious complication. Muscle proteins clog kidney filtration, leading to reduced urine output or kidney failure. In severe cases, temporary dialysis may be needed.

Compartment Syndrome

Compartment syndrome occurs when swelling inside muscle compartments restricts blood flow, causing extreme pain and potential muscle death. Emergency surgery (fasciotomy) may be required to relieve pressure.

Disseminated Intravascular Coagulation (DIC)

This life-threatening condition causes abnormal blood clotting throughout the body. DIC is more likely when CPK levels are extremely elevated and can lead to multi-organ failure.

Abnormal Heart Rhythms

Electrolyte imbalances can interfere with the electrical activity of the heart, leading to irregular or fatal arrhythmias. Continuous heart monitoring is crucial for severe cases.

Prognosis

With prompt treatment, most people recover fully from rhabdomyolysis and resume normal activities within days. However, if kidney damage occurs, recovery may take longer.

Mortality rates range between 8% and 20%, depending on the severity and presence of organ complications. Those without kidney or liver involvement generally recover well, though some may develop chronic kidney disease even after initial recovery.