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Interpreting abnormal liver tests
First set the pattern — hepatocellular (ALT and AST) or cholestatic (ALP and GGT) by the R ratio — then do a focused work-up: serology, iron and autoimmunity for hepatocellular, and ultrasound for cholestatic, asking whether the bile ducts are dilated.
Why it matters in the exam
Liver test questions give a table of values and ask for the pattern and cause. The R ratio (ALT over its upper limit, divided by ALP over its upper limit) above 5 = hepatocellular, below 2 = cholestatic, and between 2 and 5 = mixed. Fixed clues: AST twice ALT or more points to alcohol; values above 1000 point to ischaemic injury, paracetamol, acute viral hepatitis, autoimmune hepatitis or a passed bile duct stone; a high ALP with a normal GGT points to bone rather than liver. The hepatocellular work-up checks hepatitis B and C, ferritin and transferrin saturation (haemochromatosis), ANA, smooth muscle antibodies and IgG (autoimmune), ceruloplasmin in a young person (Wilson), alpha-1 antitrypsin, coeliac disease, thyroid and drugs.
In a cholestatic pattern the ultrasound decides: dilated ducts — obstruction outside the liver (stone, tumour; MRCP or ERCP); non-dilated ducts — AMA antibodies for primary biliary cholangitis (a middle-aged woman with itch, treated with ursodeoxycholic acid), MRCP for primary sclerosing cholangitis (in IBD patients), drugs and infiltrative diseases. In fatty liver (MASLD), the commonest cause, fibrosis is estimated with the FIB-4 index: below 1.3 — low risk; above 2.67 — high risk, with referral for elastography. Isolated unconjugated bilirubin in a healthy young person that rises with fasting or illness is usually Gilbert syndrome, once haemolysis is excluded.
Key points
- R ratio: above 5 hepatocellular, below 2 cholestatic.
- Above 1000: ischaemia, paracetamol, viral, autoimmune, stone.
- Cholestatic: ultrasound — dilated = obstruction; not dilated = AMA and MRCP.
- Fatty liver: FIB-4 below 1.3 low, above 2.67 high.
- ALP with normal GGT = bone; isolated unconjugated bilirubin = Gilbert after excluding haemolysis.
Summary table
| Pattern | Finding | Work-up | Exam note |
|---|---|---|---|
| Hepatocellular | R above 5, high ALT and AST | HBV, HCV, ferritin, ANA, IgG, ceruloplasmin, drugs, ultrasound | AST/ALT above 2 → alcohol |
| Above 1000 | Acute injury | Ischaemia, paracetamol, viral, autoimmune, stone | Paracetamol → N-acetylcysteine |
| Cholestatic | R below 2, high ALP and GGT | Ultrasound: dilated ducts? | ALP with normal GGT → bone |
| Cholestatic without dilation | Woman with itch; or IBD | AMA (PBC) or MRCP (PSC) | PBC: ursodeoxycholic acid |
| Fatty liver | Mildly high ALT, metabolic syndrome | FIB-4: below 1.3 low; above 2.67 high | Elastography if not low risk |
| Unconjugated bilirubin | Healthy young person, rises with fasting | Exclude haemolysis | Gilbert — no treatment needed |
A free exam question
מה נכון לגבי המהלך הטבעי של Non-Alcoholic Fatty Liver Disease ( NAFLD ?) (the question as examined, in Hebrew)
- א. NAFLD מהווה גורם סיכון מוגבר להתפתחות HCC גם בחולים ללא שחמת
- ב. NAFLD לא מהווה גורם סיכון להתפתחות Cholangiocarcinoma
- ג. כ- 25% מהחולים עם כבד שומני יפתחו שחמת תוך 20 שנה
- ד. NAFLD יכולה להתפתח רק באנשים עם עודף משקל ועמידות לאינסולין
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Sources
- ACG Clinical Guideline: Evaluation of Abnormal Liver Chemistries, 2017 — Hepatocellular versus cholestatic patterns and work-up
- AASLD Practice Guidance on the clinical assessment and management of nonalcoholic fatty liver disease, 2023 — FIB-4 and elastography
- Harrison's Principles of Internal Medicine, 21st edition (2022) — Evaluation of Liver Function
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.