What are Liver Function Tests (LFTs)?

Liver Function Tests (LFTs) are a group of blood tests used to assess the health and function of the liver. They measure enzymes, proteins and substances processed by the liver, helping detect inflammation, injury, obstruction or impaired liver function.

This extended panel includes:

• Alanine Aminotransferase (ALT) – liver cell injury
• Aspartate Aminotransferase (AST) – liver and muscle damage
• Alkaline Phosphatase (ALP) – bile duct and bone health
• Gamma-Glutamyltransferase (GGT) – bile flow and alcohol-related injury
• Total Bilirubin – liver processing and bile excretion
• Albumin – liver protein synthesis
• Ferritin – iron storage and liver iron overload

Together, these markers provide a comprehensive overview of liver health and metabolic stress on the liver.

Why do I need Liver Function Tests?

Liver disease often develops silently. LFTs help identify liver stress or damage early, before symptoms appear.

You may need Liver Function Tests if you:

• Have fatigue or unexplained weakness
• Have abdominal discomfort or jaundice
• Drink alcohol regularly
• Take long-term medication
• Have metabolic syndrome or diabetes
• Have fatty liver disease risk
• Have abnormal previous blood tests
• Need routine health screening

Symptoms and conditions linked to abnormal LFTs include:

• Fatigue
• Yellowing of skin or eyes (jaundice)
• Dark urine or pale stools
• Abdominal pain
• Nausea
• Swelling in legs or abdomen
• Iron overload (haemochromatosis)

Benefits of Liver Function Tests

• Comprehensive liver assessment
  Evaluates multiple aspects of liver health.
• Detects liver inflammation early
  Identifies enzyme elevation before symptoms.
• Assesses bile duct function
  ALP and GGT reflect bile flow problems.
• Evaluates liver protein production
  Albumin reflects synthetic function.
• Screens for iron overload
  Ferritin identifies excess iron storage.
• Supports alcohol-related liver monitoring
  GGT is sensitive to alcohol effects.
• Useful in medication monitoring
  Detects drug-induced liver injury.
• Simple blood test
  Single sample, wide clinical value.

Step by step – how the test works

You can access Liver Function Tests UK-wide through two options:

1. Clinic appointment
   Attend your nearest UK clinic where a healthcare professional will take your blood sample.
2. At-home or hotel visit (£60 extra)
   A qualified phlebotomist comes to your home or hotel, so you don’t need to travel.

Your sample is analysed in an accredited UK laboratory and results are delivered securely.

Your results explained

Low levels

• Low albumin may indicate chronic liver disease or malnutrition
• Low enzymes are usually not clinically significant

Typical UK reference context:

• Albumin: 35–50 g/L

Normal levels

• Suggest healthy liver function and iron balance

Typical UK reference context:

• ALT: < 40 U/L
• AST: < 40 U/L
• ALP: 30–130 U/L
• GGT: < 50 U/L
• Bilirubin: < 21 µmol/L
• Ferritin: 30–400 µg/L (sex-dependent)

High levels

• Raised ALT/AST → liver inflammation or damage
• Raised ALP/GGT → bile duct obstruction or cholestasis
• Raised bilirubin → impaired bile excretion
• Raised ferritin → iron overload or inflammation

Results should always be interpreted in clinical context.