Expansion
Each tissue releases a characteristic enzyme profile when damaged
Expansion
| Enzyme | Main sources | Clinical use |
|---|---|---|
| ALT | Liver (most specific) | Hepatocellular injury |
| AST | Liver, heart, muscle, red cells | Less specific; AST:ALT ratio |
| ALP | Liver (biliary), bone, placenta, gut | Cholestasis or bone turnover |
| GGT | Liver, biliary | Confirms hepatic origin of raised ALP; raised by alcohol and enzyme inducers |
| Creatine kinase | Skeletal muscle, heart, brain | Rhabdomyolysis, myopathy, statin toxicity |
| Amylase | Pancreas, salivary glands | Pancreatitis, but also perforation, ischaemia, ectopic pregnancy, parotitis |
| Lipase | Pancreas | More specific and stays raised longer than amylase |
| LDH | Ubiquitous | Haemolysis, tumour lysis, lymphoma bulk, non-specific |
| Troponin | Cardiac muscle | Myocardial injury |
Two recurring traps. A raised amylase does not equal pancreatitis: the level correlates poorly with severity, it falls within days so a late presentation may be normal, and other intra-abdominal catastrophes raise it.
A raised AST with normal ALT should prompt consideration of muscle, haemolysis or cardiac sources rather than liver, and checking creatine kinase resolves it.