Critical Alerts

• AKI occurs in 15-50%: Aggressive IV fluids are key to prevention
• Hyperkalemia can be fatal: Monitor potassium closely; treat aggressively
• CK >5000 is high risk for AKI: Threshold for aggressive hydration
• Compartment syndrome may coexist: Check compartments in trauma
• Target urine output 200-300 mL/hr: High-volume fluid resuscitation
• Avoid nephrotoxins: NSAIDs, contrast, aminoglycosides

Key Diagnostics

Emergency Treatments

Overview

Rhabdomyolysis is the breakdown of skeletal muscle fibers with release of intracellular contents (myoglobin, creatine kinase, potassium, phosphate) into the bloodstream. It ranges from asymptomatic CK elevation to life-threatening acute kidney injury (AKI) and fatal hyperkalemia.

Classification

By Severity:

By Cause:

Epidemiology

• Incidence: 26,000+ hospitalizations/year in US
• AKI incidence: 15-50% of rhabdomyolysis patients
• Mortality: 5% overall; higher with AKI and dialysis
• Most common causes: Trauma (30%), drugs/toxins (30%), immobilization (15%)

Etiology

Common Causes:

Drug-Induced Rhabdomyolysis:

Life-Threatening Complications

High-Risk Features

• CK >15,000 U/L
• Pre-existing CKD
• Diabetes
• Sepsis
• Delayed presentation
• Initial creatinine elevation

Other Causes of Elevated CK

Other Causes of Dark Urine

Laboratory Studies

Urinalysis Interpretation

Positive blood without RBCs = Myoglobinuria (or hemoglobinuria)

ECG

• Monitor for hyperkalemia changes:
  • Peaked T waves
  • Prolonged PR
  • Wide QRS
  • Sine wave (pre-arrest)

Imaging

• CK/labs confirm diagnosis
• Imaging for underlying cause or complications:
  • CT/MRI: Muscle necrosis, abscess
  • Compartment pressure: If clinical concern
  • Venous Doppler: DVT (from immobility)

ICU Admission Criteria

• CK >15,000-20,000 U/L
• Acute kidney injury
• Significant hyperkalemia
• Hemodynamic instability
• Need for dialysis
• Underlying critical illness

Floor Admission

• Moderate CK elevation (5,000-15,000)
• Stable renal function
• No significant electrolyte derangement

Discharge Criteria

• CK trending down
• Creatinine stable or improving
• Adequate oral intake
• No electrolyte abnormalities
• Cause addressed

Follow-Up

Condition Explanation

• "Your muscle cells have broken down, releasing their contents into your blood."
• "This can affect your kidneys and cause dangerous changes in your blood salt levels."
• "We need to give you a lot of fluids to flush your kidneys and keep them working."

Prevention

• Gradual increase in exercise intensity
• Adequate hydration during exercise
• Avoid extreme exertion in heat
• Know signs of overexertion

Medication Awareness

• Report muscle pain on statins immediately
• Avoid combining statins with certain medications

Warning Signs for Return

• Return of muscle pain or weakness
• Dark urine
• Decreased urine output
• Swelling of limbs
• Palpitations or lightheadedness

Exertional Rhabdomyolysis

• More common in unconditioned individuals
• Seen with novel exercise ("weekend warriors")
• NSAID use increases AKI risk
• Prevention: Gradual training, hydration

Statin-Induced

• Risk factors: High-dose, CYP3A4 inhibitors, hypothyroidism
• Discontinue statin; usually resolves
• Rechallenge with different statin after resolution (with caution)

Crush Injury / Earthquake Victims

• "Crush syndrome": Massive rhabdomyolysis + AKI + hyperkalemia
• Start fluids before extrication if possible
• Prepare for dialysis
• Consider tourniquet to prevent reperfusion flush

Pediatric

• Viral myositis is common cause
• Genetic metabolic myopathies
• Generally good prognosis

Elderly

• Prolonged immobility is common cause
• Higher AKI risk
• More comorbidities

Performance Indicators

Documentation Requirements

• Suspected or confirmed cause
• Initial CK and peak CK
• Urine output and fluid administration
• Potassium trend and treatment
• Creatinine trend
• Disposition plan

Diagnostic Pearls

• CK is very sensitive: Can be elevated before symptoms
• Dipstick positive blood without RBCs = myoglobinuria: Classic finding
• Check for compartment syndrome in trauma: Pain out of proportion
• CK >5000 = high risk for AKI: Threshold for aggressive management
• Ask about drugs and exercise: Most common modifiable causes
• Serum myoglobin is less useful: Clears before CK

Treatment Pearls

• Fluids are the mainstay: Target UO 200-300 mL/hr
• Don't wait for AKI to start fluids: Prevention is key
• Bicarbonate not routinely recommended: May worsen hypocalcemia
• Don't give calcium for asymptomatic hypocalcemia: May deposit in muscle
• Treat hyperkalemia aggressively: It can kill quickly
• Stop offending drugs: Statins, cocaine, etc.

Disposition Pearls

• ICU for CK >15,000-20,000 or AKI: Close monitoring needed
• Monitor CK until trending down: May continue to rise for 1-3 days
• Recurrent rhabdomyolysis: Consider metabolic myopathy workup
• Statin rechallenge possible: With different agent, low dose, monitoring