Abnormal liver blood test

Normal Liver Function Test Ranges

  • ALT: 10-50 U/L
  • AST: 10-40 U/L
  • ALP: 30-130 U/L
  • GGT: 1-55 U/L
  • Total Bilirubin: <21 µmol/L
  • Albumin: 35-50 g/L
  • Total Protein: 60-80 g/L
  • Globulin: 20-35 g/L

common patterns of abnormal liver function tests

  • Hepatocellular pattern: significant rise in ALT and AST (ALT > AST)
  • Cholestatic pattern: raised ALP and GGT (ALT/AST normal or mildly raised)
  • Alcohol-related pattern: raised AST > ALT (AST:ALT ratio > 2), raised GGT
  • Isolated hyperbilirubinaemia: raised bilirubin, normal ALT, AST, ALP
  • Low albumin pattern: low albumin, other values normal
  • Bone-related ALP rise: raised ALP, normal GGT

Primary care action guide for abnormal LFTs

  • ALT > AST (hepatocellular): consider NAFLD, viral hepatitis, drug injury
    → check hepatitis B surface antigen (HBsAg), hepatitis C antibody (anti-HCV), ferritin, ANA, arrange liver ultrasound
    repeat in 6–8 weeks
  • AST > ALT (alcohol-related): suggests alcohol use
    → check GGT, FBC and check MCV this might be raised, offer referral to alcohol cessation service
    repeat in 6 weeks after alcohol reduction
  • Raised ALP & GGT (cholestatic): think bile duct obstruction or primary biliary cholangitis (PBC)
    → repeat LFT, ANA/AMA, GGT, Immunoglobulins, ferritin/transferrin, request an liver ultrasound
    repeat in 2–4 weeks
  • Isolated ALP raised (normal GGT): likely bone source
    → check calcium, phosphate, vitamin D
    repeat in 3 months if clinically indicated
  • Isolated bilirubin raised: likely Gilbert’s or haemolysis
    → check FBC, reticulocytes, haptoglobin (if available)
    no repeat needed if diagnosis confirmed and patient well
  • Low albumin: suggests chronic liver disease or systemic illness
    → check clotting screen, full liver screen
    repeat in 4–6 weeks or sooner if clinically unwell

Refer if Any of the Following Apply

  • LFTs remain abnormal after 3 months
  • ALT persistently >100 U/L
  • ALP or bilirubin persistently raised
  • Evidence of liver failure (low albumin, raised INR)
  • Positive autoantibodies or unexplained hepatomegaly
  • If ALP/GGT abnormal on repeat with or without abnormal USS

urgent 2ww referral if any of the following apply

  • Jaundice, low albumin <35 g/L, or prolonged INR >1.3 (synthetic failure)
  • Weight loss or marked cholestasis (suspected malignancy)
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