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← Gastroenterology and hepatology indexChapter sections
Purpose and principlesIndications, selection and cautionsMethod and interpretationClinical next stepsProcedure and medicine safetyRisks, monitoring and follow-upSpecial situationsCommon pitfallsQuestionsSources
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Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.

Abnormal liver blood tests

Gastroenterology and hepatology · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

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Time-critical presentation

New hepatic injury with coagulopathy and any encephalopathy is acute liver failure until proved otherwise. Check glucose and paracetamol exposure, begin immediate supportive treatment and contact a transplant-linked liver service urgently. Pain, fever and jaundice with cholestatic tests suggests infected biliary obstruction and requires emergency sepsis care plus biliary source-control assessment.

Purpose and principles

Interpret abnormal liver blood tests by biochemical pattern, severity, synthetic function and clinical context; identify acute liver failure or obstruction promptly; and complete a proportionate aetiology and fibrosis assessment rather than repeatedly sampling without a plan.

A standard adult liver panel commonly includes bilirubin, albumin, alanine aminotransferase, alkaline phosphatase and gamma-glutamyltransferase, with a full blood count adding platelet information. Aspartate aminotransferase, INR and other tests are added when the question requires them. ALT and AST rise with hepatocyte injury; ALP and GGT suggest cholestasis; bilirubin reflects conjugation and excretion; albumin and INR help assess synthesis, although both have important non-hepatic determinants. Results must therefore be interpreted as a pattern rather than labelled collectively as 'LFTs'.

The history should establish alcohol exposure in units and pattern, metabolic risk, viral exposure, travel, family history, pregnancy where relevant, autoimmune symptoms, biliary pain, pruritus, systemic infection and every medicine or supplement. Examination seeks jaundice, chronic liver disease, hepatosplenomegaly, ascites, encephalopathy and haemodynamic instability. Compare prior results and time course: an acute hepatocellular injury differs from stable mild ALT elevation, and a new cholestatic picture with pain or fever may represent urgent biliary obstruction.

Indications, selection and cautions

Hepatocellular pattern

ALT or AST predominates over ALP. Consider viral or autoimmune hepatitis, drug-induced injury, ischaemia, muscle injury and metabolic liver disease; very high acute values focus the differential but do not name the cause.

Cholestatic patternRed flag

ALP and GGT predominate, often with conjugated bilirubin, pruritus, pale stool or dark urine. Pain, fever and jaundice suggest infected obstruction and need urgent biliary assessment.

Acute liver failure phenotypeRed flag

New hepatic injury with coagulopathy and any encephalopathy in a person without known cirrhosis is a time-critical syndrome. Check glucose, paracetamol exposure and acid-base state and contact a transplant-linked liver service urgently.

Isolated bilirubin

Fractionate bilirubin and assess haemolysis. Unconjugated, intermittent elevation with otherwise normal tests may fit Gilbert syndrome, but anaemia, reticulocytosis or symptoms require another explanation.

Advanced disease with quiet enzymes

Thrombocytopenia, splenomegaly, nodular liver, low albumin, raised INR, ascites or varices may reveal portal hypertension despite normal or modest ALT.

Method and interpretation

  1. 01
    Repeat and extended liver panelFirst step
    Why
    Confirm the pattern with bilirubin, ALT, ALP, GGT, albumin, FBC and INR when synthetic dysfunction or acute illness is possible; add AST, creatine kinase or fractionated bilirubin selectively.
    Interpretation and limitations
    Trends provide timing, but a repeat test is not an investigation plan. Falling aminotransferases can indicate recovery or loss of viable liver, so interpret alongside INR, bilirubin, glucose and clinical state.
  2. 02
    Adult liver aetiology screen
    Why
    Arrange ultrasound, hepatitis B surface antigen, hepatitis C antibody with PCR confirmation, antimitochondrial, antinuclear and smooth-muscle antibodies, serum immunoglobulins, ferritin and transferrin saturation as locally specified.
    Interpretation and limitations
    Positive markers require confirmatory interpretation. Ferritin is an acute-phase reactant; low-titre antibodies can be incidental; negative screening does not exclude every inherited, infiltrative or drug-related cause.
  3. 03
    Abdominal ultrasound with biliary assessment
    Why
    Assess steatosis, liver contour, focal lesions, portal vein, gallbladder, bile-duct calibre, spleen and ascites.
    Interpretation and limitations
    Duct dilatation supports obstruction, but early obstruction may have normal-calibre ducts. Ultrasound detects steatosis but is insensitive for mild fat and cannot stage fibrosis reliably.
  4. 04
    Non-invasive fibrosis assessment

Clinical next steps

01EmergencyAcute jaundice or major injuryFirst stepNew jaundice, very abnormal enzymes, coagulopathy, hypoglycaemia, confusion or systemic instability.+
  1. 1Use ABCDE, bedside glucose, sepsis assessment and a complete medication and overdose history; send urgent liver, renal, coagulation, gas, lactate and paracetamol tests.
  2. 2Stop plausible hepatotoxins where safe, start time-critical antidotal or sepsis treatment under the relevant protocol, and image promptly for obstruction or vascular disease.
  3. 3Discuss early with gastroenterology or hepatology; any suspected acute liver failure requires urgent contact with a transplant-linked liver unit, not routine referral.
  4. 4Trend INR, glucose, lactate, renal function, bilirubin and mental state because aminotransferase movement alone is insufficient.
02PatternStructured outpatient evaluationStable unexplained abnormal liver tests without emergency features.+

Procedure and medicine safety

Replenishes glutathione after paracetamol toxicity and may be recommended by specialists in selected non-paracetamol acute liver failure.

Acetylcysteine

Use the current weight-based intravenous emergency regimen for paracetamol poisoning or specialist-advised acute liver failure; verify the live UK toxicology and local protocol.

Anaphylactoid reactions, fluid volume and dosing errors require monitoring. Never delay treatment while awaiting a late or uncertain overdose history; consult NPIS or TOXBASE through authorised clinical access.

Binds bile acids and can reduce cholestatic itch while the underlying cause is investigated and treated.

Cholestyramine

A locally selected oral regimen for troublesome cholestatic pruritus, separated from other medicines by the interval in the current BNF.

Constipation, poor palatability and binding of warfarin, thyroxine, digoxin and fat-soluble vitamins. It does not relieve an obstructed infected biliary system.

Stopping a credible offending exposure is central to drug-induced liver injury management.

Suspected hepatotoxic medicine management

No generic dose: withhold, continue or substitute only after weighing causality, indication and withdrawal risk with pharmacy and the responsible specialist.

Do not abruptly stop essential anticonvulsants, corticosteroids or immunosuppressants without a safe plan. Report qualifying reactions through current MHRA systems.

Risks, monitoring and follow-up

  • Trend bilirubin, ALT or AST, ALP, albumin, INR, FBC, glucose and renal function at a frequency matched to acuity rather than a fixed universal interval.
  • Reassess mental state, haemodynamics, urine output, bleeding, infection and hypoglycaemia frequently in acute injury.
  • Record alcohol and medication changes, symptoms and adherence; verify that abnormal viral, immune or iron results reach the correct specialist pathway.
  • For metabolic liver disease, monitor weight, diabetes, blood pressure, lipids and cardiovascular risk alongside periodic fibrosis reassessment.
  • Escalate if bilirubin or INR rises, platelets fall, symptoms appear or imaging shows portal hypertension, obstruction or a focal lesion even if ALT improves.
  • Close the loop on incidental imaging and late laboratory results with a named clinician and a communicated plan.

Special situations

Function is not enzyme activity

A high ALT can coexist with preserved synthesis, while advanced cirrhosis can have normal ALT and poor reserve. Use precise language when explaining results.

GGT solves one narrow problem

GGT helps identify a hepatobiliary source of raised ALP but is nonspecific and often rises with alcohol, obesity and medicines.

Context beats the reference range

A new result just inside the laboratory range may be important for that patient, while a stable minor deviation can be constitutional. Compare baseline and trajectory.

Fibrosis risk is a separate question

Finding likely steatotic liver disease does not stage it. A formal non-invasive fibrosis pathway identifies the smaller group at risk of liver outcomes.

Ultrasound can miss early obstruction

Bile ducts may not yet be dilated, particularly early or with intermittent blockage. Escalate imaging when the clinical probability remains high.

Common pitfalls

  1. 01

    Calling every component a liver-function test and equating raised ALT with liver failure.

  2. 02

    Repeating the panel months later without an aetiology screen, imaging or result owner.

  3. 03

    Dismissing mild abnormalities in a patient with metabolic risk, harmful alcohol use or thrombocytopenia.

  4. 04

    Diagnosing alcohol-related injury from GGT alone.

  5. 05

    Missing muscle injury as a source of AST or bone disease as a source of ALP.

  6. 06

    Waiting for encephalopathy to worsen before discussing possible acute liver failure.

Practice

Two practice questions

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Question 1 of 2
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Gastroenterology and hepatologyOriginal SBA

Cholestatic emergency

An adult has fever, right upper-quadrant pain, jaundice, hypotension and a newly cholestatic liver profile. What is the best immediate management approach?

Choose one answer, then submit
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Sources and review status4 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • BSG guideline on abnormal liver blood testsUK pattern recognition, aetiology-screen and referral framework.
  • NICE NG50: Cirrhosis in over 16sAssessment and complications of suspected or established cirrhosis.
  • BSG and BASL quality standards for fatty liver diseaseNon-invasive fibrosis risk stratification and metabolic care.
  • NICE CG188: Gallstone diseaseUltrasound, MRCP and duct-clearance pathway.

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateComplete draftClinical stateAwaiting reviewJurisdictionUnited Kingdom

The BSG approach is to investigate persistent or otherwise unexplained abnormalities rather than rely on magnitude or duration alone. A standard adult aetiology screen includes abdominal ultrasound, hepatitis B surface antigen, hepatitis C antibody with confirmatory PCR when positive, autoimmune serology and immunoglobulins, and iron studies. Further tests are phenotype-led. People with steatosis or metabolic risk require non-invasive fibrosis assessment because ultrasound and aminotransferases cannot stage fibrosis. Indeterminate or high-risk results need transient elastography, ELF testing or hepatology review according to local pathways.

Key points

  • Liver enzymes describe injury or cholestasis, not liver function: bilirubin, albumin, INR and the clinical state provide different information about excretion and synthetic reserve.
  • Classify the dominant pattern as hepatocellular, cholestatic, isolated bilirubin or mixed, then compare with the patient's baseline and the timing of symptoms, medicines and exposures.
  • The size of an abnormality does not reliably predict significance: mild persistent tests can mark advanced fibrosis, while very high aminotransferases narrow the acute differential.
  • Acute jaundice with confusion, hypoglycaemia, coagulopathy, severe systemic illness or rapidly worsening tests requires same-day specialist escalation and an acute liver failure pathway.
  • Raised ALP with raised GGT supports hepatobiliary origin; a normal GGT makes bone, placental or other non-hepatic ALP sources more likely but does not replace clinical assessment.
  • Do not simply repeat unexplained abnormalities indefinitely. Complete an adult liver aetiology screen and ultrasound, then risk-stratify fibrosis where metabolic or alcohol-related disease is plausible.
  • Take a precise history of prescribed, over-the-counter, herbal, recreational and performance-enhancing substances, including start dates, dose changes and dechallenge.
First line
Why
Use an age-aware first-line score such as FIB-4 followed by transient elastography or ELF according to the local metabolic or alcohol-related liver pathway.
Interpretation and limitations
Low-risk scores can support community management; indeterminate or high-risk results need second-line testing or referral. Acute hepatitis, age and platelet disorders can distort scores.
  • 05
    Acute injury tests
    Why
    For marked or symptomatic acute injury obtain paracetamol concentration, venous or arterial gas and lactate, glucose, renal profile, viral studies, pregnancy test where relevant and targeted toxicology or autoimmune testing.
    Interpretation and limitations
    A late paracetamol concentration may be undetectable despite toxicity. Do not wait for a complete panel before discussing acute liver failure or starting indicated antidotal treatment.
  • 06
    MRCP, CT or specialist imaging
    Why
    Escalate imaging for persistent cholestasis, suspected obstruction, vascular disease, infiltrative disease or a focal lesion not resolved by ultrasound.
    Interpretation and limitations
    Choose the modality for the question: MRCP maps ducts non-invasively, CT assesses acute complications and malignancy, and ERCP is primarily therapeutic.
    • 1
    Confirm the dominant biochemical pattern and review alcohol, metabolic risks, medicines, supplements, viral exposure, family history and previous results.
  • 2Complete the standard adult liver aetiology screen and ultrasound rather than repeating the same panel in isolation.
  • 3Second lineApply phenotype-led second-line tests and fibrosis risk stratification; refer cholestatic, autoimmune, viral, iron-overload, focal-lesion or advanced-fibrosis signals appropriately.
  • 4EscalationDocument the result owner, planned interval and explicit escalation criteria.
    • 03CholestasisPossible biliary obstructionCholestatic tests with jaundice, pain, fever, pruritus or ductal concern.+
    1. 1Assess for cholangitis using physiology and sepsis features; obtain blood cultures and start local antibiotics promptly when infection is suspected.
    2. 2Request urgent ultrasound, then MRCP, EUS or CT according to stability and the likely level or cause of obstruction.
    3. 3AlternativeArrange therapeutic ERCP or alternative drainage urgently when infected obstruction or persistent clinically important blockage is present.
    4. 4Do not let a non-dilated duct on early ultrasound overrule a convincing deteriorating syndrome.
    Normal aminotransferases do not exclude advanced cirrhosis, and low albumin may reflect inflammation, renal loss or malnutrition rather than hepatic failure.