LFT Panel Explained
| Test | Normal | Role | Rises With |
|---|---|---|---|
| ALT (alanine transaminase) | 7–56 U/L | Hepatocellular damage marker | Hepatitis, NAFLD, drugs, alcohol |
| AST (aspartate transaminase) | 10–40 U/L | Hepatocellular damage (less specific) | Hepatitis, alcohol (AST:ALT >2:1), muscle disease |
| ALP (alkaline phosphatase) | 44–147 U/L | Biliary/bone/placenta | Cholestasis, bone disease, pregnancy |
| GGT (gamma-GT) | 10–71 U/L | Biliary and alcohol marker | Alcohol, drugs, cholestasis |
| Bilirubin (total) | <21 μmol/L | Bile pigment (from RBC breakdown) | Jaundice: hepatic, post-hepatic, pre-hepatic |
| Albumin | 35–50 g/L | Liver synthetic function | Low in chronic liver disease, malnutrition |
| PT / INR | INR 0.8–1.2 | Clotting factor synthesis | Synthetic failure in acute/chronic liver disease |
Pattern Recognition
| Pattern | Likely Cause |
|---|---|
| ALT/AST rise >5× normal | Viral hepatitis, drug toxicity, ischaemic hepatitis, autoimmune hepatitis |
| ALP/GGT rise with mild transaminases | Cholestasis: gallstones, PBC, PSC, drug-induced |
| Isolated bilirubin rise | Gilbert's syndrome (benign), haemolysis, hepatitis |
| Low albumin + high bilirubin + raised PT | Chronic liver disease / decompensation |
AST:ALT RatioAn AST:ALT ratio >2:1 in an alcoholic patient strongly suggests alcoholic hepatitis. In NAFLD, ALT usually exceeds AST. This ratio helps differentiate causes without additional tests.
What causes high ALT?
The most common causes are NAFLD (fatty liver), alcohol, viral hepatitis B or C, medications (statins, paracetamol overdose, antibiotics), and autoimmune hepatitis.
Is slightly raised ALT serious?
Mildly raised ALT (1–3× normal) is very common and often caused by NAFLD or alcohol. Sustained elevations >3× normal or rising trend warrants ultrasound and further investigation.
What is Gilbert's syndrome?
A benign genetic condition where bilirubin conjugation is mildly impaired, causing intermittently elevated bilirubin (especially during fasting or illness). It's harmless and requires no treatment.
What does a low albumin mean?
Low albumin reflects either reduced liver synthesis (chronic liver disease), protein loss (nephrotic syndrome, protein-losing enteropathy), or malnutrition. It's a key prognostic marker in liver disease.
Medical Disclaimer: This page is for general education only and does not replace professional medical advice. Always consult a qualified healthcare provider.