What are the signs and treatment of rhabdomyolysis (muscle breakdown disease)?

From the Guidelines

Rhabdomyolysis can start to show in the urine as early as a few hours after muscle injury, with myoglobin being detectable in the urine within 2-12 hours after the onset of muscle damage. The signs and symptoms of rhabdomyolysis include severe muscle pain, weakness, swelling, dark urine (tea or cola-colored), decreased urination, fatigue, nausea, vomiting, confusion, and irregular heartbeat.

Diagnosis and Treatment

The diagnosis of rhabdomyolysis involves measuring plasma myoglobin, plasma creatine phosphokinase (CPK), and potassium levels, as well as monitoring urine output and pH 1. Treatment primarily involves aggressive intravenous fluid administration to maintain urine output and prevent kidney damage.

• Aggressive intravenous fluid administration, typically normal saline at rates of 200-1000 mL/hour initially to maintain urine output of 200-300 mL/hour
• Monitoring and correction of electrolyte abnormalities, particularly hyperkalemia, hypocalcemia, and hyperphosphatemia
• Discontinuation of any contributing medications and rest of the affected muscles
• Avoidance of NSAIDs which can worsen kidney stress

Prognosis and Recovery

Recovery from rhabdomyolysis typically takes days to weeks depending on severity, with most patients regaining normal kidney function if treated promptly 1. However, in severe cases with acute kidney injury or dangerously high potassium levels, dialysis may be necessary. It is essential to identify and address the underlying cause of rhabdomyolysis, whether it's medication-related, trauma, excessive exercise, or other factors.

From the Research

Signs of Rhabdomyolysis

• Rhabdomyolysis is characterized by the rapid breakdown of skeletal muscle with release of electrolytes, myoglobin, and other proteins into the circulation 2
• The clinical presentation encompasses a spectrum of patients ranging from those with asymptomatic increases in creatine kinase (CK) levels to those with fulminant disease complicated by acute kidney injury (AKI), severe electrolyte abnormalities, compartment syndrome, and disseminated intravascular coagulation 2
• A CK level at least 10 times the upper limit of normal typically is considered diagnostic, as is myoglobinuria 2
• Myoglobin has been identified as the primary muscle constituent contributing to renal damage in rhabdomyolysis 3

Treatment of Rhabdomyolysis

• Management consists of rapidly initiating aggressive intravenous saline resuscitation to maintain a urine output of at least 300 mL/hour 2
• Sodium bicarbonate can be used for patients who are acidotic, and mannitol can be used for those whose urine output is not at goal 2
• However, recent studies suggest that neither bicarbonate nor mannitol administration improved the incidence of acute renal failure and need for dialysis in patients with rhabdomyolysis 4
• Early and aggressive fluid resuscitation to restore renal perfusion and increase urine flow is agreed on as the main intervention for preventing and treating AKI 3
• Hyperkalemia and compartment syndrome are additional complications of rhabdomyolysis that must be treated effectively 3

Time Frame for Myoglobinuria

• Although the exact time frame for myoglobinuria to appear in the urine after muscle injury is not specified in the studies, it is known that myoglobinuria is a diagnostic criterion for rhabdomyolysis 2
• The development of rhabdomyolysis is associated with a wide variety of diseases, injuries, medications, and toxins, and the time frame for myoglobinuria to appear may vary depending on the cause and severity of the condition 5

Complications and Prognosis

• AKI is the most significant complication of rhabdomyolysis, occurring in 4%-33% of patients 5
• The overall prognosis for rhabdomyolysis is favourable when treated with early and aggressive IVF resuscitation, and full recovery of renal function is common 5
• However, the mortality rate may still be as high as 8% regardless of the cause of rhabdomyolysis 5