From the Guidelines
Yes, rhabdomyolysis (rhabdo) can cause acute kidney injury (AKI). Rhabdomyolysis occurs when damaged muscle tissue releases proteins and electrolytes into the bloodstream, particularly myoglobin. This myoglobin is filtered by the kidneys and can cause direct toxicity to kidney tubules, tubular obstruction, and renal vasoconstriction, all of which contribute to kidney damage. The risk of AKI increases with the severity of muscle damage and is more likely when creatine kinase levels exceed 5,000-10,000 U/L, as seen in patients with crush syndrome following an earthquake, where CPK levels above 75,000 IU/L were associated with a high incidence of newly formed acute kidney injury (>80%) 1.
Key Factors Contributing to AKI in Rhabdomyolysis
- Myoglobin release and its toxic effects on kidney tubules
- Severity of muscle damage, as indicated by high CPK levels
- Delayed initiation of volume resuscitation, which can exacerbate kidney injury 1
Recommendations for Management
- Aggressive intravenous fluid administration (typically isotonic saline at 1-2 L/hour initially, then adjusted based on urine output targeting 200-300 mL/hour) to flush myoglobin from the kidneys
- Monitoring kidney function through creatinine, BUN, and electrolytes is essential
- Addressing the underlying cause of rhabdomyolysis to prevent further muscle breakdown and kidney injury
- Consideration of early fasciotomy in cases of established compartment syndrome, which can contribute to the development of rhabdomyolysis and subsequent AKI 1
Detection and Prevention of AKI
- Repeated bio-assessment combining plasma myoglobin, plasma creatine phosphokinase (CPK), and kalaemia measurements can help detect acute kidney injury in patients with post-traumatic acute rhabdomyolysis 1
- Bladder catheterization to monitor hourly urine output and urine pH, which should be maintained at 6.5, can also aid in early detection of AKI 1
From the Research
Rhabdomyolysis and Acute Kidney Injury (AKI)
- Rhabdomyolysis is a condition characterized by muscle damage and the release of intracellular muscle contents into the circulation, which can lead to acute kidney injury (AKI) 2, 3.
- The pathophysiological mechanisms of renal injury in rhabdomyolysis include renal vasoconstriction, intraluminal cast formation, and direct myoglobin toxicity 3.
- AKI occurs in 33-50% of patients with rhabdomyolysis, and early diagnosis and treatment are crucial to reduce the risk of AKI 3, 4.
Causes and Risk Factors
- The causes of rhabdomyolysis are multifactorial and include direct muscular injury, strenuous exercise, drugs, toxins, infections, hyperthermia, seizures, metabolic and/or electrolyte abnormalities, and endocrinopathies 3, 5.
- Agitation, increased motor activity, and certain medications such as venlafaxine can also contribute to the development of rhabdomyolysis and subsequent AKI 4.
Treatment and Management
- Early implementation of fluid therapy appears to be crucial in the treatment of rhabdomyolysis and AKI 2, 3.
- Electrolyte disturbances should be detected and treated early, and the use of bicarbonates or diuretics may be helpful in some cases 2, 4.
- Renal replacement therapy may be necessary in severe cases of AKI due to rhabdomyolysis 2, 5, 6.