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

Common Patterns of Abnormal LFTs

• Hepatocellular pattern: ALT and AST raised (ALT usually higher)
• Cholestatic pattern: ALP and GGT raised
• Alcohol-related pattern: AST > ALT (ratio > 2) with raised GGT
• Isolated bilirubin rise: other enzymes normal
• Low albumin: may indicate chronic liver disease or systemic illness
• Isolated ALP rise with normal GGT: likely bone source

Primary Care Action Guide

Mild ALT / AST elevation (< 3× upper limit)

• Review alcohol intake
• Review medications (statins, antibiotics, herbal remedies)
• Check hepatitis B surface antigen and hepatitis C antibody
• Check ferritin (exclude haemochromatosis)
• Consider HbA1c and lipid profile (NAFLD risk)
• Arrange liver ultrasound if persistent
• Repeat LFTs in 6-8 weeks

AST > ALT (suspected alcohol)

• Check GGT
• Check FBC (MCV may be raised)
• Offer alcohol reduction support
• Repeat LFTs in 6 weeks after reduction

Cholestatic pattern (Raised ALP + GGT)

• Repeat LFTs to confirm
• Check AMA (for primary biliary cholangitis)
• Check immunoglobulins
• Arrange liver ultrasound
• Repeat within 2-4 weeks

Isolated ALP rise (normal GGT)

• Likely bone source
• Check calcium, phosphate, vitamin D
• Repeat in 3 months if clinically appropriate

Isolated bilirubin rise

• Consider Gilbert’s syndrome
• Check FBC and reticulocytes (exclude haemolysis)
• No repeat needed if diagnosis clear and patient well

Urgent Referral to Secondary Care If:

• ALT or AST > 5× upper limit
• Rapidly rising bilirubin
• Jaundice with systemic symptoms
• Signs of liver failure (confusion, ascites, coagulopathy)
• Suspected acute hepatitis

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)