From the Guidelines
In patients with rhabdomyolysis, elevated troponin and CK levels are expected, with CK being the primary diagnostic marker, and treatment should focus on aggressive IV fluid administration to prevent acute kidney injury, as evidenced by the guidelines for acute care of severe limb trauma patients 1. When evaluating patients with rhabdomyolysis, it is essential to consider the clinical context to differentiate between cardiac injury and skeletal muscle damage.
- CK levels are typically markedly elevated, often exceeding 5,000-10,000 U/L and sometimes reaching 100,000 U/L or higher, reflecting extensive muscle breakdown 1.
- Troponin elevation in rhabdomyolysis occurs due to skeletal muscle damage rather than cardiac injury, as some troponin isoforms are present in skeletal muscle 1.
- To differentiate between cardiac injury and rhabdomyolysis, clinicians should consider the clinical context, evaluate CK-MB fraction, and assess troponin trends over time 1.
- Additional testing like ECG and echocardiogram may be necessary to rule out cardiac involvement.
- Raising CPK levels above five times normal (approximately 1000 IU/L) is a sign of rhabdomyolysis, and levels above 75,000 IU/L were associated with a high incidence of newly formed acute kidney injury (>80%) 1.
- Myoglobin is responsible for intraluminal kidney tubular obstruction resulting in reduced glomerular filtration rate, and its measurement may be more sensitive and specific than CPKs in identifying the risk of acute kidney injury 1.
From the Research
Elevated Troponin and CK in Rhabdomyolysis
- Rhabdomyolysis refers to the breakdown of skeletal muscle with subsequent release of intracellular contents into blood, causing elevated creatine kinase (CK) and renal damage 2.
- The condition can lead to acute kidney injury (AKI), with studies suggesting that AKI occurs in 33-50% of patients with rhabdomyolysis 3.
- Elevated CK levels are a key diagnostic marker for rhabdomyolysis, with levels typically five times higher than the normal value confirming the condition 3.
- However, there have been cases reported where rhabdomyolysis-associated AKI has occurred with normal creatine phosphokinase (CPK) levels, highlighting the need for careful evaluation and monitoring of patients 4.
Causes and Risk Factors
- Rhabdomyolysis can be caused by various factors, including direct muscular injury, strenuous exercise, drugs, toxins, infections, hyperthermia, seizures, metabolic and/or electrolyte abnormalities, and endocrinopathies 3.
- Traumatic compartment syndrome is a significant risk factor for rhabdomyolysis, with a high percentage of patients developing the condition (44.2%) 5.
- History of illicit drugs or alcohol use, as well as ischemic injury, are also significant predictive factors for rhabdomyolysis 5.
Diagnosis and Treatment
- Early diagnosis and aggressive fluid resuscitation are crucial in preventing and treating AKI associated with rhabdomyolysis 6.
- Elevated troponin levels may also be observed in rhabdomyolysis, although the relationship between troponin and CK levels is not fully understood 2.
- Treatment is aimed at discontinuation of further skeletal muscle damage, prevention of acute renal failure, and rapid identification of potentially life-threatening complications 6.