From the Guidelines
Rhabdomyolysis causes acute tubular necrosis, a type of intrinsic acute kidney injury (AKI), due to the release of myoglobin into the circulation, which precipitates in kidney tubules and causes direct toxicity. This type of AKI is often seen in patients with severe limb trauma, crush injuries, or other conditions that result in significant muscle damage 1. The diagnosis of AKI due to rhabdomyolysis is based on laboratory findings, including elevated creatine kinase (CK) levels, myoglobinuria, and hyperkalemia 1.
Some key points to consider in the management of AKI due to rhabdomyolysis include:
- Aggressive fluid resuscitation with isotonic saline to maintain urine output and prevent further kidney damage 1
- Monitoring of electrolytes, particularly potassium, calcium, and phosphorus, to prevent complications such as hyperkalemia and hypocalcemia
- Avoidance of nephrotoxic medications and adjustment of dosages of renally cleared drugs to prevent further kidney injury 1
- Consideration of urine alkalinization with sodium bicarbonate to prevent myoglobin precipitation, although the evidence for this is limited
- Early identification of at-risk patients and prompt treatment to prevent the development of AKI and improve outcomes
In terms of specific management strategies, the use of IV fluids at 10-15 mL/kg/hr, aiming for urine output of 200-300 mL/hr, is recommended until myoglobinuria clears 1. Additionally, the measurement of plasma myoglobin, which has an earlier peak plasma concentration than CK, may be more sensitive and specific than CK in identifying the risk of AKI 1.
Overall, the management of AKI due to rhabdomyolysis requires a multifaceted approach that includes aggressive fluid resuscitation, monitoring of electrolytes and kidney function, and avoidance of nephrotoxic medications. By prioritizing these strategies, healthcare providers can help to prevent the development of AKI and improve outcomes for patients with rhabdomyolysis.
From the Research
Causes of Acute Kidney Injury (AKI) due to Rhabdomyolysis
- Rhabdomyolysis is a clinical and biochemical syndrome that occurs when skeletal muscle cells disrupt and release creatine phosphokinase (CK), lactate dehydrogenase (LDH), and myoglobin into the interstitial space and plasma 2
- The main causes of rhabdomyolysis include direct muscular injury, strenuous exercise, drugs, toxins, infections, hyperthermia, seizures, metabolic and/or electrolyte abnormalities, and endocrinopathies 2
- Rhabdomyolysis can occur due to a variety of causes, including traumatic, non-traumatic, non-traumatic exertional, and non-traumatic non-exertional categories 3
Pathophysiology of Renal Injury
- The main pathophysiological mechanisms of renal injury are renal vasoconstriction, intraluminal cast formation, and direct myoglobin toxicity 4, 2
- Myoglobin toxicity is a key factor in the development of AKI in rhabdomyolysis 4, 2
Management of AKI due to Rhabdomyolysis
- Early diagnosis and prompt management with fluid resuscitation, initiation of renal replacement therapy (RRT), and elimination of causative agents can help prevent complications 4
- Aggressive intravenous hydration is crucial in the management of rhabdomyolysis-induced AKI 3
- The use of bicarbonates or diuretics may also be helpful, but especially in the latter case, the indications should be well evaluated, remembering to avoid hypovolemia 5
- Renal replacement therapy is often implemented due to water-electrolyte or acid-base disorders 5, 3
Diagnosis of Rhabdomyolysis-Induced AKI
- Elevated creatine phosphokinase (CPK) of at least 5 times the upper limit of normal is an important diagnostic marker of rhabdomyolysis 6
- However, CPK alone may not be a sensitive marker for rhabdomyolysis-induced AKI in some cases, and other diagnostic tools such as urinalysis and kidney biopsy may be necessary 6