What is the best course of treatment for a patient with Rhabdomyolysis, particularly those with a history of intense physical activity, trauma, or underlying medical conditions like hypothyroidism?

Rhabdomyolysis Treatment

Immediately initiate aggressive intravenous fluid resuscitation with isotonic saline (0.9% NaCl), targeting urine output of 300 mL/hour, as this is the cornerstone of treatment and delayed initiation significantly increases the risk of acute kidney injury. 1

Immediate Fluid Resuscitation

• Start IV crystalloid resuscitation immediately upon diagnosis, even if CK levels are only mildly elevated, as early intervention is critical to prevent progression to acute kidney injury 1
• Use isotonic saline (0.9% NaCl) as the initial fluid of choice for volume expansion 1
• Administer >6L of fluid per day for severe rhabdomyolysis (CK >50,000 IU/L) and 3-6L per day for moderate cases (CK 15,000-50,000 IU/L) 2, 1, 3
• Target urine output of ≥300 mL/hour to facilitate myoglobin clearance and prevent renal tubular obstruction 1, 3
• Monitor closely for fluid overload, particularly in patients with cardiac or renal compromise 1

Critical Electrolyte Management

• Check potassium levels immediately and monitor every 6-12 hours in severe cases, as hyperkalemia can precipitate life-threatening cardiac arrhythmias and cardiac arrest 2, 1, 3
• Perform immediate ECG to assess for arrhythmias related to hyperkalemia 3
• Correct significant electrolyte abnormalities promptly, including hypocalcemia and hyperphosphatemia 2, 1
• Perform repeated bioassessment including plasma myoglobin, CK, and potassium measurements 2
• Assess for metabolic acidosis with arterial blood gas, which commonly occurs in severe rhabdomyolysis 2, 3

Medication Review and Discontinuation

• Immediately discontinue any causative agents, particularly statins, which are the most common drug cause of rhabdomyolysis (incidence 1.6 per 100,000 patient-years) 2
• Stop all high-risk supplements including red yeast rice containing lovastatin, creatine monohydrate, wormwood oil, licorice, and Hydroxycut 2, 1
• Cease the physical activity that triggered the event 1

Monitoring and Laboratory Surveillance

• Trend CK levels daily until declining, and continue IV fluids typically until CK <1,000 U/L 3
• Monitor renal function (creatinine, BUN) daily until stable 1, 3
• Check comprehensive metabolic panel including calcium, phosphorus, and magnesium 3
• Monitor urine output hourly with bladder catheterization; inadequate output (<300 mL/hour) suggests worsening kidney function 1
• Perform urinalysis to assess for myoglobinuria (brown urine positive for blood without RBCs) 3

Compartment Syndrome Surveillance

• Maintain high suspicion for compartment syndrome, which can both cause and complicate rhabdomyolysis 2, 1
• Early signs include pain, tension, paresthesia, and paresis; late signs include pulselessness and pallor (indicating irreversible damage) 2, 1
• Perform early fasciotomy for established compartment syndrome 2
• Consider fasciotomy when compartment pressure exceeds 30 mmHg or when differential pressure (diastolic BP – compartment pressure) is <30 mmHg 2, 1

Advanced Interventions for Severe Cases

• Initiate renal replacement therapy (RRT) if CK remains persistently elevated despite 4 days of adequate hydration, as this indicates severe rhabdomyolysis with significant risk of irreversible kidney damage 1
• Consider RRT for refractory hyperkalemia, severe metabolic acidosis, or progressive acute kidney injury 1
• After ensuring adequate volume expansion, a diuretic challenge with furosemide may help assess kidney function in select cases 1

Pain Management Strategy

• Use acetaminophen (500-1000 mg) as the preferred initial analgesic, with a maximum daily dose of 4-6 grams, as it avoids nephrotoxic effects 2
• Avoid all NSAIDs (ibuprofen, ketoprofen, diclofenac, naproxen, mefenamic acid) due to their gastrointestinal and renal toxicity 2
• Reserve opioids for severe muscle pain unresponsive to acetaminophen; use oral morphine (20-40 mg for opioid-naive patients) as first-line opioid 2
• In patients with established acute kidney injury (eGFR <30 ml/min), use fentanyl or buprenorphine as the safest opioid choices 2

Special Considerations for Underlying Conditions

Hypothyroidism

• Investigate for hypothyroidism with thyroid function tests if no other obvious cause is apparent, as severe hypothyroidism can cause rhabdomyolysis 2, 3, 4
• Hypothyroidism predisposes patients to muscle toxicity, especially when taking statins 2
• Treat with oral levothyroxine in accordance with endocrine consultation 4

Trauma-Related Rhabdomyolysis

• In trauma patients with severe limb injury, avoid iterative tourniquet releases, as this aggravates local muscle injury and systemic rhabdomyolysis 5
• Reassess tourniquet effectiveness, usefulness, and location as soon as possible to limit morbidity 5

Critical Pitfalls to Avoid

• Do not delay fluid resuscitation, as this is associated with higher risk of acute kidney injury and worse outcomes 2, 1
• Do not use inadequate fluid volumes (<6L/day in severe cases), as this may fail to prevent renal complications 1
• Do not miss hyperkalemia monitoring, as failure to correct it can lead to pulseless electrical activity and cardiac arrest 2, 1
• Do not overlook compartment syndrome, particularly in traumatic or severe exertional cases, as this can result in irreversible muscle and nerve damage 1
• Recognize that CK levels peak 24-120 hours after the inciting event, so current levels may not represent the peak 2, 1