Elevated Liver Enzymes in Rhabdomyolysis
Yes, liver enzymes—particularly AST—are commonly elevated in rhabdomyolysis, with AST elevation occurring in approximately 93% of cases and ALT elevation in approximately 75% of cases with creatine kinase (CK) ≥1,000 U/L. 1
Mechanism and Pattern of Elevation
AST is significantly more elevated than ALT in rhabdomyolysis because AST is present in skeletal muscle, whereas ALT exists in much lower concentrations in muscle tissue. 2, 3 This creates a characteristic pattern where:
- AST elevations are more pronounced and occur more frequently than ALT elevations 1
- AST concentrations decrease in parallel with CK levels during recovery from rhabdomyolysis, confirming skeletal muscle as the primary source 1
- The AST:ALT ratio is typically elevated (AST > ALT) in rhabdomyolysis, similar to the pattern seen in alcoholic liver disease 4
Clinical Significance and Diagnostic Implications
The aminotransferase elevation in rhabdomyolysis creates a diagnostic dilemma because these enzymes lack tissue specificity to distinguish primary liver injury from muscle injury. 5 Key considerations include:
- In only 1 out of 215 cases of rhabdomyolysis was ALT >40 U/L while AST remained <40 U/L, demonstrating that isolated ALT elevation essentially excludes rhabdomyolysis as the cause 1
- AST is associated with both peak CK levels and severity of rhabdomyolysis (P = 0.002 for peak CK; P = 0.015 for severity) 6
- The presence of concurrent liver disease does not significantly alter the aminotransferase pattern in rhabdomyolysis 4
Practical Diagnostic Approach
When encountering elevated aminotransferases, measure creatine kinase (CK) to differentiate muscle injury from primary liver disease. 2, 3 The diagnostic algorithm should proceed as follows:
- If AST is disproportionately elevated compared to ALT (AST >> ALT), strongly consider rhabdomyolysis and check CK immediately 1, 4
- If CK is markedly elevated (≥1,000 U/L), the aminotransferase elevation is likely from skeletal muscle rather than liver injury 1, 6
- Monitor AST levels in parallel with CK during the first 6 days—if both decline together, this confirms muscle as the source 1
- Avoid unnecessary liver investigations such as viral hepatitis serologies, autoimmune markers, or liver biopsy when rhabdomyolysis is confirmed 5
Common Pitfalls to Avoid
Do not assume elevated aminotransferases automatically indicate liver disease without checking CK, especially in patients with risk factors for rhabdomyolysis such as recent intensive exercise, prolonged surgery, statin use, or trauma. 7, 6 The classic triad of rhabdomyolysis (muscle pain, weakness, and dark urine) is often absent in mild cases, making biochemical markers essential for diagnosis. 7
Rhabdomyolysis should be considered first when AST-dominant aminotransferase elevation occurs in patients with suspicious skeletal muscle injury, even before considering alcoholic liver disease. 4 The median peak AST in rhabdomyolysis (221 U/L) is significantly higher than in alcoholic liver disease (103 U/L), though both conditions can show AST > ALT patterns. 4