What are the symptoms of rhabdomyolysis?

Symptoms of Rhabdomyolysis

Rhabdomyolysis presents with a classic triad of muscle pain, muscle weakness, and dark tea/cola-colored urine (myoglobinuria), though this complete triad appears in less than 10% of cases. 1, 2

Primary Clinical Manifestations

• Muscle symptoms:

  • Muscle pain (myalgia), particularly in proximal muscle groups
  • Muscle weakness
  • Muscle tenderness
  • Muscle swelling
  • Muscle stiffness
  • Cramping
  • Fatigue

• Urinary changes:

  • Dark tea or cola-colored urine (myoglobinuria)
  • Decreased urine output (in cases with acute kidney injury)

• Systemic symptoms:

  • Fatigue
  • Fever
  • Malaise
  • Nausea/vomiting
  • Confusion (in severe cases)

Laboratory Findings

Laboratory tests are essential for confirming rhabdomyolysis:

• Elevated creatine kinase (CK) - typically at least 10 times the upper limit of normal 1
• Positive urine myoglobin - rises earlier than CK but has a shorter half-life 1
• Urinalysis - positive for blood on dipstick but negative for RBCs on microscopy 1
• Electrolyte abnormalities - hyperkalemia, hypocalcemia, hyperphosphatemia
• Elevated creatinine - indicating acute kidney injury
• Elevated liver enzymes (AST, ALT) - released from damaged muscle 3

Diagnostic Approach

When evaluating a patient with suspected rhabdomyolysis:

1. Monitor CK levels every 6-12 hours in the acute phase 1
2. Test for myoglobinuria - a key diagnostic indicator 1
3. Obtain ECG to assess for cardiac complications and effects of electrolyte abnormalities 1
4. Consider imaging (MRI, CT, ultrasound) to evaluate muscle involvement in unclear cases 2

Complications to Monitor

• Acute kidney injury - occurs in 13-50% of cases 4
• Compartment syndrome - presenting with pain, tension, paresthesia, and paresis in affected limbs 1
• Severe electrolyte disturbances - particularly life-threatening hyperkalemia
• Disseminated intravascular coagulation - in severe cases 2

Special Considerations

• In patients on statin therapy, unexplained severe muscle symptoms or fatigue should prompt immediate discontinuation of the statin and evaluation for rhabdomyolysis with CK, creatinine, and urinalysis for myoglobinuria 5
• Rhabdomyolysis can be misdiagnosed as psychiatric illness when presenting with dark urine and muscle pain 3
• Patients with recurrent episodes should be evaluated for underlying genetic disorders 1

Common Pitfalls

• Delayed diagnosis due to absence of the complete classic triad in most patients
• Misattribution of symptoms to other conditions like psychiatric disorders 3
• Failure to recognize rhabdomyolysis in the context of statin therapy 5
• Inadequate monitoring of complications, particularly acute kidney injury

Early recognition and aggressive fluid resuscitation are crucial to prevent acute kidney injury, the most serious complication of rhabdomyolysis.