Liver Profile (LFT) Explained: Understanding AST, ALT, Bilirubin, ALP, GGT and Protein Tests

What Is a Liver Profile?

A liver profile, sometimes called a liver function test (LFT) panel, is a group of blood tests commonly used to assess different aspects of liver and biliary system health.

Importantly, a liver profile is not a single test. Instead, it combines multiple laboratory measurements that provide information about:

• Liver-cell injury
• Bile flow and bile duct function
• Jaundice patterns
• Protein production by the liver
• Liver synthetic function
• Chronic liver disease

Doctors rarely interpret individual results in isolation. The pattern of abnormalities across multiple tests often provides more useful information than any single number.

Main Components of a Liver Profile

Different laboratories may include slightly different tests, but most liver profiles contain the following components.

AST and ALT: Liver-Cell Injury Pattern

AST and ALT are enzymes found within liver cells. When liver cells become irritated, inflamed or injured, AST and ALT may leak into the bloodstream.

This pattern is often called the hepatocellular pattern because the primary abnormality involves liver cells themselves.

Common situations associated with elevated AST and ALT include:

• Fatty liver disease
• Viral hepatitis
• Medication-related injury
• Alcohol-related liver injury
• Autoimmune liver disease

Bilirubin: Jaundice and Yellow Eyes

Bilirubin is a yellow pigment produced during the normal breakdown of red blood cells. Doctors often use bilirubin levels to evaluate:

• Jaundice
• Yellow eyes
• Bile flow problems
• Haemolysis (red blood cell breakdown)
• Liver processing and excretion

Bilirubin is commonly reported as total bilirubin, direct bilirubin and indirect bilirubin. The pattern of elevation — and in particular whether direct bilirubin is raised — can provide important clues regarding the underlying cause.

ALP and GGT: Bile Flow and Cholestatic Patterns

ALP and GGT are particularly useful when doctors suspect problems involving bile flow. This pattern is often called the cholestatic pattern because it reflects impaired bile drainage.

Common situations include:

• Gallstones
• Bile duct obstruction
• Cholestasis
• Biliary inflammation

GGT is especially useful because it helps determine whether a high ALP is likely coming from the liver and bile ducts or from another source such as bone. A raised direct bilirubin alongside ALP and GGT may also point toward a cholestatic or bile-flow pattern.

Albumin, Globulin and A/G Ratio

Albumin and globulin are proteins measured in many liver profiles.

Albumin is produced mainly by the liver and helps maintain fluid balance within blood vessels. Globulins are a group of proteins involved in immune function and inflammation. The albumin/globulin ratio (A/G ratio) may provide additional clues when interpreted alongside the individual values.

Unlike AST and ALT, protein abnormalities often reflect longer-term processes rather than recent liver-cell injury.

Albumin and INR: Liver Synthetic Function Pattern

The liver does more than process toxins and produce bile. It also makes important proteins needed by the body, including albumin and several clotting factors.

Because of this, doctors may use albumin and INR together to assess the liver's synthetic function — meaning the liver's ability to produce important blood proteins and clotting factors.

For a deeper explanation of clotting tests and synthetic function, read our PT/INR guide.

Common Liver Profile Patterns

Doctors usually focus on overall patterns rather than isolated results. The combination of which tests are abnormal often guides next steps more than any individual number.

What Does an Abnormal Liver Profile Mean?

An abnormal liver profile does not automatically mean severe liver disease. Interpretation depends on:

• Which tests are abnormal
• Degree of abnormality
• Symptoms
• Trend over time
• Medical history
• Medications
• Imaging results

Some abnormalities may be temporary, while others require further investigation. A doctor should always be involved in interpreting liver profile results.

How doctors approach an abnormal liver profile

Doctors usually follow a pattern-based approach when interpreting abnormal liver profile results.

Common causes of abnormal liver profile results

Many different conditions can affect liver profile results. The pattern of abnormality usually guides which causes are considered first.

Can Liver Disease Exist with Normal Liver Tests?

Yes. Normal liver profile results do not completely exclude liver disease. Examples include:

• Early fatty liver disease
• Early fibrosis
• Some chronic liver conditions

Blood tests are only one part of a complete assessment. Doctors may also consider symptoms, physical examination, ultrasound findings and risk factors when evaluating liver health.

What a liver profile cannot tell you

A liver profile is useful, but it cannot always identify the exact cause of abnormal results by itself.

For example, a liver profile alone may not be able to confirm:

• The exact cause of hepatitis
• Whether fatty liver has caused scarring
• The exact site of bile duct obstruction
• Whether a low albumin is due to liver disease, kidney loss, nutrition or inflammation
• Whether a high INR is due to liver dysfunction, medication effect or vitamin K-related issues

This is why doctors may combine blood tests with ultrasound scans, hepatitis tests, autoimmune markers, INR/PT, full blood count and other investigations when needed.

When Should You Seek Medical Advice?

Medical review is recommended when liver profile abnormalities are significant, persistent, rising over time or associated with symptoms.

• New or worsening jaundice
• Yellow eyes
• Dark urine
• Pale stools
• Abdominal pain
• Fever
• Persistent itching
• Vomiting
• Unexplained weight loss
• Bleeding tendency or easy bruising
• Confusion or severe drowsiness
• Known chronic liver disease
• High INR or suspected clotting abnormality
• Persistent abnormalities on repeat testing

Frequently asked questions