AST and ALT Elevation After Traumatic Falls
Yes, AST and ALT are commonly elevated after traumatic falls, with approximately 49% of polytrauma patients showing elevated transaminases, and these elevations can occur from both direct liver injury and non-hepatic sources such as muscle damage. 1
Mechanisms of Enzyme Elevation After Trauma
Direct Liver Injury
- Blunt hepatic trauma directly elevates ALT with high sensitivity. In patients with blunt abdominal trauma, raised serum ALT is a sensitive diagnostic marker for liver injury—all 31 patients with liver injury in one cohort had elevated ALT, while no patient with normal ALT had hepatic injury. 2
- The magnitude of ALT elevation correlates with injury severity: patients with modestly raised ALT typically resolve with non-operative management, whereas those with marked elevations have more serious hepatic injuries, greater transfusion requirements, and higher mortality rates. 2
- For pediatric trauma specifically, all children with blunt liver injury and AST/ALT levels ≤50 IU/L required only conservative treatment with no complications. 3
Muscle Injury (Non-Hepatic Source)
- AST is less specific than ALT because it is present in cardiac muscle, skeletal muscle, kidneys, brain, and red blood cells, making it commonly elevated from muscle trauma alone. 4, 5
- In acute muscle injury from trauma, both AST and ALT are elevated, but the AST/ALT ratio is typically >3 initially, then approaches 1 after several days due to faster AST decline. 6
- Check creatine kinase (CK) levels to differentiate muscle injury from liver injury—markedly elevated CK confirms muscle origin of transaminase elevation. 4, 5, 7
Clinical Significance and Diagnostic Approach
When to Suspect Liver Injury
- ALT is the more specific marker for hepatic injury because it is primarily concentrated in liver tissue with minimal presence in other organs. 4, 8
- In blunt abdominal trauma, elevated ALT (>50 IU/L) warrants further evaluation for liver injury with imaging, as five patients with significantly raised ALT and negative ultrasound were found to have liver injury on subsequent evaluation. 2
- Normal ALT and AST levels (≤50 IU/L) have high negative predictive value for clinically significant liver injury in hemodynamically stable patients, potentially reducing the need for CT imaging, particularly in pediatric populations. 3
Monitoring and Management
- In polytrauma rehabilitation patients, 49% present with elevated ALT (≥44 IU/L) within 30 days of injury, regardless of mechanism or extent of trauma. 1
- For the majority of these patients, enzymes return to normal with conservative management, and no specific etiology is defined in most cases. 1
- Repeat liver enzymes in 2-4 weeks to establish trend if initial elevation is present without clear indication for immediate intervention. 4
Important Caveats
Pitfalls to Avoid
- Do not assume all transaminase elevations after trauma represent liver injury—muscle damage from the fall itself commonly elevates AST and can elevate ALT. 5, 6
- AST elevation following myocardial infarction (which can occur in severe trauma) may be mistaken for liver injury. 8
- In chronic muscle injury patterns, AST and ALT levels become comparable due to differences in half-life, potentially confusing the clinical picture. 6
When Imaging is Indicated
- Hemodynamically unstable patients require immediate imaging regardless of enzyme levels. 9
- Elevated transaminases with clinical signs of peritonitis or hemodynamic instability warrant urgent CT evaluation. 2
- In pediatric patients, AST and ALT combined with ultrasound can reach 88% sensitivity and 96% negative predictive value, making this a cost-effective screening approach in resource-limited settings. 9