[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Clinical skills](https://durgical.com/en/clinical-skills/) › [Reading lab results](https://durgical.com/en/clinical-skills/areas/labs/) › Liver tests: hepatocellular or cholestatic?

# Liver tests: hepatocellular or cholestatic?

- Interpretation

Blood tests that show whether liver cells are injured, bile flow is blocked, or the liver is failing to make its proteins.

Updated Nov 13, 2026

## Key points

- Pattern first: hepatocellular (ALT and AST lead), cholestatic (ALP and GGT lead), mixed, or isolated bilirubin.
- R ratio = (ALT ÷ its upper limit) ÷ (ALP ÷ its upper limit): above 5 hepatocellular, below 2 cholestatic, 2 to 5 mixed.
- Aminotransferases in the thousands: ischaemic hepatitis, acute viral hepatitis, or paracetamol (acetaminophen) or other drug toxicity.
- An AST:ALT ratio above 2 with a raised GGT suggests alcohol-related liver disease.
- Albumin and INR measure synthetic function; a high INR with confusion after an acute injury means acute liver failure.

## What it is

The so-called liver function tests are mostly markers of injury, not of function. The aminotransferases (ALT and AST) leak from damaged liver cells; ALT is more specific to the liver, while AST is also found in heart, skeletal muscle, kidney and red cells. Alkaline phosphatase (ALP) and gamma-glutamyl transferase (GGT) rise when bile flow is impaired; ALP also comes from bone, the placenta and the intestine, and a raised GGT alongside it confirms a hepatobiliary source. Bilirubin is split into unconjugated (indirect), raised by haemolysis or poor conjugation as in Gilbert syndrome, and conjugated (direct), raised in liver cell disease and cholestasis. The true tests of synthetic function are albumin and the prothrombin time or INR, which can stay normal until disease is advanced. The reading question is which pattern dominates: hepatocellular (aminotransferases out of proportion to ALP), cholestatic (ALP and GGT out of proportion), mixed, or isolated hyperbilirubinaemia. The pattern, the size and speed of the rise and the clinical story then narrow the causes, and an ultrasound separates obstruction of the large ducts from cholestasis inside the liver.

## Reference values and concepts

- Usual adult ranges (they vary by laboratory): ALT 7–56 U/L, AST 10–40 U/L, ALP 44–147 U/L.
- Total bilirubin 0.1–1.2 mg/dL; conjugated (direct) bilirubin below 0.3 mg/dL; jaundice is usually visible above about 2.5–3 mg/dL.
- Albumin 3.5–5.0 g/dL; its long half-life (about 3 weeks) means it falls late, and it also falls in malnutrition, nephrotic syndrome and inflammation.
- The prothrombin time and INR rise when the liver cannot make clotting factors; vitamin K deficiency from cholestasis does the same and corrects with vitamin K.
- ALT is more liver-specific than AST; AST also rises with muscle injury, so check creatine kinase when AST leads without another explanation.
- GGT rises with cholestasis, alcohol and enzyme-inducing drugs; a raised ALP with a normal GGT suggests bone, pregnancy or growth in children.

## Reading it step by step

- Confirm the abnormality and compare with old results — a single mild rise in a well patient is often repeated before a full workup.
- Decide which is more raised for its upper limit, ALT or ALP — this splits hepatocellular from cholestatic causes.
- Calculate the R ratio when the pattern is unclear — above 5 is hepatocellular, below 2 cholestatic, between them mixed.
- Grade the size of the rise — mild (under 5 times normal), marked, or in the thousands, each with its own short list of causes.
- Look at bilirubin and its fractions — unconjugated alone points to haemolysis or Gilbert; conjugated to the liver or bile ducts.
- Check albumin and INR — they show whether the liver still makes its proteins and how ill the patient is.
- If ALP leads, confirm a liver source with GGT, then ultrasound — dilated ducts mean obstruction; non-dilated, a cause inside the liver.
- Match with the history: alcohol, drugs, supplements, travel, viral risk factors, metabolic syndrome, pregnancy — they choose the targeted tests.

## Patterns of liver tests and what they suggest

| Pattern | Typical results | Think of | Next test |
| --- | --- | --- | --- |
| [Hepatocellular, very high](https://durgical.com/en/conditions/viral-hepatitis/) | ALT and AST in the thousands | Acute viral hepatitis, ischaemic hepatitis, paracetamol or other drug toxicity | Drug level, viral serology, recent low blood pressure, INR |
| [Hepatocellular, mild to moderate](https://durgical.com/en/conditions/metabolic-dysfunction-associated-steatotic-liver-disease/) | ALT and AST under about 5 times normal | Fatty liver, alcohol, chronic viral hepatitis, drugs, autoimmune hepatitis, haemochromatosis | Ultrasound, serology, iron studies, autoantibodies |
| [Alcohol pattern](https://durgical.com/en/conditions/alcoholic-liver-disease/) | AST:ALT above 2, raised GGT | Alcohol-related liver disease | Alcohol history, INR, platelets |
| [Cholestatic, dilated ducts](https://durgical.com/en/conditions/choledocholithiasis/) | ALP, GGT and conjugated bilirubin high | Common bile duct stone, pancreatic or bile duct cancer | Ultrasound, then MRCP or ERCP |
| [Cholestatic, non-dilated ducts](https://durgical.com/en/conditions/primary-biliary-cholangitis/) | ALP and GGT high | Drugs, primary biliary cholangitis, primary sclerosing cholangitis, infiltration | Antimitochondrial antibody, MRCP, drug review |
| [ALP high, GGT normal](https://durgical.com/en/conditions/paget-disease-of-bone/) | ALP raised alone | Bone (growth, Paget disease, metastases), pregnancy | Calcium, bone imaging, age and pregnancy status |
| [Isolated unconjugated bilirubin](https://durgical.com/en/conditions/gilbert-syndrome/) | Indirect bilirubin up, enzymes normal | Gilbert syndrome, haemolysis | Blood count, reticulocytes, LDH, haptoglobin, smear |
| [Synthetic failure](https://durgical.com/en/conditions/cirrhosis/) | Low albumin, high INR, low platelets | Cirrhosis, acute liver failure | Ultrasound, senior review, look for encephalopathy |

## Patterns and common mistakes

- Calling every abnormal result 'liver failure': most rises are injury markers; failure means a high INR, low albumin, jaundice or encephalopathy.
- Missing a source outside the liver: AST from muscle (exercise, rhabdomyolysis), ALP from bone or pregnancy, unconjugated bilirubin from haemolysis.
- Normal aminotransferases do not exclude cirrhosis: a scarred liver may show normal enzymes with low albumin, high INR and low platelets.
- Paracetamol (acetaminophen) poisoning may show normal tests early; the time of ingestion and the drug level decide treatment, not the first ALT.
- Mild isolated unconjugated hyperbilirubinaemia that rises with fasting or illness, with normal enzymes and no haemolysis, is typical of Gilbert syndrome.
- Fever, jaundice and right upper quadrant pain with a cholestatic pattern is cholangitis until proven otherwise.
- Drug-induced injury with ALT above 3 times normal and bilirubin above 2 times normal (Hy's law) carries a high risk of a severe outcome.

## Next step

- Signs of acute liver failure (raised INR, confusion) or suspected paracetamol overdose: call a senior now; overdose needs a timed drug level and the antidote acetylcysteine by protocol.
- Cholestatic pattern: request an abdominal ultrasound; dilated ducts lead to imaging of the biliary tree and possibly ERCP, and fever with jaundice is an emergency.
- Hepatocellular pattern: viral serology (hepatitis A IgM, hepatitis B surface antigen and core IgM, hepatitis C antibody), autoantibodies, iron studies, and ceruloplasmin in young patients.
- Stop suspected liver-toxic drugs and supplements, ask about alcohol, and repeat the panel to follow the trend.
- Mild persistent rise: look for metabolic dysfunction-associated fatty liver with an ultrasound, assess fibrosis risk, and refer if it persists.

## Test yourself

Think of the answer, then tap the question to see it.

## Case: ALT 1,850 U/L and ALP 160 U/L (upper limits 56 and 147 U/L) the day after a period of shock. What is the pattern and likely cause?

R ratio ≈ (1850 ÷ 56) ÷ (160 ÷ 147) ≈ 30: hepatocellular, in the thousands; after shock think ischaemic hepatitis, which falls quickly once perfusion returns.

## A 70-year-old has painless jaundice, ALP 520 U/L, high GGT, mildly raised ALT and dilated bile ducts on ultrasound. What must be excluded?

An obstructive cholestatic pattern: a distal obstruction such as cancer of the pancreatic head or bile duct, or a stone; next, cross-sectional imaging of the pancreas and biliary tree.

## A healthy 22-year-old has bilirubin 2.4 mg/dL, mostly unconjugated, after fasting, with normal enzymes and blood count. What is the likely diagnosis?

Gilbert syndrome: reduced conjugation that worsens with fasting or illness; confirm there is no haemolysis (normal haemoglobin, reticulocytes, LDH and haptoglobin) and reassure.

## Which liver tests reflect synthetic function, and why may they be normal in early disease?

Albumin and the prothrombin time or INR; the liver has a large reserve and albumin has a long half-life, so they change only when much function is lost.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/clinical-skills/liver-tests-hepatocellular-or-cholestatic/)

## Elsewhere in DurgiPedia

- [Liver function tests: reading the pattern](https://durgical.com/en/biochemistry/topics/liver-function-tests-reading-the-pattern/)
- [Bilirubin](https://durgical.com/en/biochemistry/molecules/bilirubin/)
- [Alanine aminotransferase (ALT, GPT)](https://durgical.com/en/biochemistry/enzymes/alanine-aminotransferase/)
- [Aspartate aminotransferase (AST, GOT)](https://durgical.com/en/biochemistry/enzymes/aspartate-aminotransferase/)
- [Serum albumin as a lab test](https://durgical.com/en/biochemistry/topics/serum-albumin-as-a-lab-test/)
- [Functions of the liver](https://durgical.com/en/physiology/functions-of-the-liver/)
- [Jaundice: prehepatic, hepatic and posthepatic](https://durgical.com/en/clinical-exam/jaundice-prehepatic-hepatic-and-posthepatic/)

## Connections

## Related 6

- [Coagulation tests: PT/INR, aPTT, fibrinogen and D-dimer](https://durgical.com/en/clinical-skills/coagulation-tests-pt-inr-aptt-fibrinogen-and-d-dimer/)
- [Reading a full blood count](https://durgical.com/en/clinical-skills/reading-a-full-blood-count/)
- [The peripheral blood smear: what to look for](https://durgical.com/en/clinical-skills/the-peripheral-blood-smear-what-to-look-for/)
- [Ascitic fluid: SAAG and infection](https://durgical.com/en/clinical-skills/ascitic-fluid-saag-and-infection/)
- [ERCP](https://durgical.com/en/clinical-skills/ercp/)
- [Electrolytes, urea and creatinine](https://durgical.com/en/clinical-skills/electrolytes-urea-and-creatinine/)

## Related conditions 11

- [Viral hepatitis](https://durgical.com/en/conditions/viral-hepatitis/)
- [Alcoholic liver disease (biochemistry)](https://durgical.com/en/conditions/alcoholic-liver-disease/)
- [Metabolic dysfunction-associated steatotic liver disease (MASLD/NAFLD)](https://durgical.com/en/conditions/metabolic-dysfunction-associated-steatotic-liver-disease/)
- [Drug-induced liver injury](https://durgical.com/en/conditions/drug-induced-liver-injury/)
- [Acetaminophen toxicity](https://durgical.com/en/conditions/acetaminophen-toxicity/)
- [Choledocholithiasis](https://durgical.com/en/conditions/choledocholithiasis/)
- [Acute cholangitis](https://durgical.com/en/conditions/acute-cholangitis/)
- [Primary biliary cholangitis](https://durgical.com/en/conditions/primary-biliary-cholangitis/)
- [Gilbert syndrome](https://durgical.com/en/conditions/gilbert-syndrome/)
- [Cirrhosis](https://durgical.com/en/conditions/cirrhosis/)
- [Acute liver failure](https://durgical.com/en/conditions/acute-liver-failure/)

## In Pharmacology 3

- [Acetylcysteine](https://durgical.com/en/pharmacology/acetylcysteine/)
- [Ursodeoxycholic acid](https://durgical.com/en/pharmacology/ursodeoxycholic-acid/)
- [Lactulose](https://durgical.com/en/pharmacology/lactulose/)

[← All clinical skills](https://durgical.com/en/clinical-skills/)

Educational content; it does not replace supervised hands-on training, your institution's protocols or a prescriber's order. A procedure is learnt with a teacher and done only once you are trained to do it.

Sources: [Liver Function Tests](https://www.ncbi.nlm.nih.gov/books/NBK482489/) (StatPearls (NCBI Bookshelf), 2026).

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/clinical-skills/liver-tests-hepatocellular-or-cholestatic/