From the Guidelines
The primary diagnostic test for rhabdomyolysis is measuring creatine kinase (CK) levels in the blood, with levels above 1000 IU/L indicating the condition, as stated in the 2021 guidelines for the acute care of severe limb trauma patients 1. When diagnosing rhabdomyolysis, it is essential to consider the following key points:
- CK levels above five times normal, approximately 1000 IU/L, are a sign of rhabdomyolysis 1
- Plasma myoglobin measurement may be more sensitive and specific than CK levels in identifying the risk of acute kidney injury, which is correlated with increased mortality 1
- Additional diagnostic tests include:
- Plasma potassium test for hyperkalaemia
- Measurement of kidney function by means of plasma creatinine test
- Urinalysis to check for myoglobinuria These tests are crucial in identifying rhabdomyolysis and its potential complications, such as acute kidney injury, compartment syndrome, and electrolyte disturbances, which can lead to serious morbidity and mortality if not promptly treated 1.
From the Research
Diagnosis of Rhabdomyolysis
The diagnosis of rhabdomyolysis involves several tests, including:
- Serum creatine kinase (CK) levels: CK is a marker of muscle damage, and elevated levels can indicate rhabdomyolysis 2, 3, 4, 5
- Urine myoglobin levels: Myoglobin is a protein released from damaged muscle cells, and its presence in the urine can indicate rhabdomyolysis 2, 3, 5
- Serum myoglobin levels: Myoglobin levels in the blood can also be used to diagnose rhabdomyolysis 2, 3
- Creatinine levels: Elevated creatinine levels can indicate kidney damage, which is a common complication of rhabdomyolysis 3, 6, 4
- Muscle biopsy: A muscle biopsy can be used to confirm the diagnosis of rhabdomyolysis and to rule out other causes of muscle weakness 5
- Genetic testing: Genetic testing can be used to identify inherited causes of rhabdomyolysis, such as disorders of glycogen metabolism or fatty acid β-oxidation 5
Interpretation of Test Results
The interpretation of test results for rhabdomyolysis includes:
- Elevated CK levels: CK levels above 5000 IU/L can indicate severe muscle damage and rhabdomyolysis 2
- Elevated myoglobin levels: Myoglobin levels above 1000 ng/mL can indicate severe muscle damage and rhabdomyolysis 3
- Elevated creatinine levels: Creatinine levels above 1.5 mg/dL can indicate kidney damage and rhabdomyolysis 3, 6, 4
- Myoglobin/CK ratio: A myoglobin/CK ratio above 0.2 can indicate an increased risk of acute kidney injury 3
Clinical Evaluation
The clinical evaluation of rhabdomyolysis includes:
- Medical history: A thorough medical history can help identify potential causes of rhabdomyolysis, such as trauma, substance abuse, or medication use 6, 5
- Physical examination: A physical examination can help identify signs of muscle damage, such as weakness, swelling, or dark pigmentation of the urine 6, 5
- Laboratory studies: Laboratory studies, such as CK and myoglobin levels, can help confirm the diagnosis of rhabdomyolysis 2, 3, 4, 5