What type of kidney injury occurs from rhabdomyolysis (rapid breakdown of skeletal muscle tissue)?

From the Guidelines

Rhabdomyolysis typically causes acute tubular necrosis (ATN), a form of acute kidney injury. This occurs when muscle breakdown releases myoglobin into the bloodstream, which is then filtered by the kidneys. Myoglobin is toxic to kidney tubules, causing direct tubular injury through several mechanisms, as noted in studies such as 1. It precipitates in the tubules, particularly in acidic urine, forming obstructive casts. Myoglobin also releases free iron which generates reactive oxygen species, causing oxidative damage to tubular cells. Additionally, myoglobin depletes nitric oxide, leading to intrarenal vasoconstriction and reduced kidney perfusion. The resulting kidney injury manifests as elevated creatinine and blood urea nitrogen levels, decreased urine output, and sometimes dark or tea-colored urine due to myoglobinuria.

Some key points to consider in the diagnosis and management of rhabdomyolysis-induced kidney injury include:

• Monitoring for signs of acute kidney injury, such as elevated serum creatinine and decreased urine output, as recommended in guidelines like those found in 1 and 1.
• Aggressive intravenous fluid administration to maintain urine output above 200-300 mL/hour, as well as correcting electrolyte abnormalities, particularly hyperkalemia.
• Addressing the underlying cause of rhabdomyolysis, which may involve treating the initial trauma or condition leading to muscle breakdown.
• In severe cases, renal replacement therapy may be necessary until kidney function recovers, highlighting the importance of early recognition and intervention, as discussed in 1.

The importance of early detection and management of acute kidney injury due to rhabdomyolysis cannot be overstated, given its potential to progress to chronic kidney disease or require ongoing renal replacement therapy, as outlined in studies such as 1 and 1. Therefore, a comprehensive approach that includes monitoring, aggressive fluid management, and addressing the underlying cause is crucial in minimizing morbidity and mortality associated with this condition.

From the Research

Type of Kidney Injury

The type of kidney injury that occurs from rhabdomyolysis is Acute Kidney Injury (AKI) 2, 3, 4, 5, 6.

Pathophysiology of Renal Injury

The main pathophysiology of renal injury is due to:

• Vasoconstriction
• Intraluminal casts
• Tubular obstruction
• Direct myoglobin toxicity 2, 3

Characteristics of Acute Kidney Injury

Acute kidney injury (AKI) occurs in 33-50% of patients with rhabdomyolysis 2, 3, 4. Key characteristics include:

• Elevated serum creatine kinase (CK) levels, usually five times higher than the normal value
• Myoglobinuria
• Metabolic acidosis
• Electrolyte imbalances 3, 4, 6

Management and Diagnosis

Early diagnosis and prompt management with:

• Fluid resuscitation
• Initiation of renal replacement therapy (RRT)
• Elimination of causative agents can help prevent complications 2, 3, 5