Your liver is one of the hardest-working organs in your body. Weighing approximately 1.5 kilograms, this remarkable organ performs over 500 essential functions — from filtering toxins and producing bile to storing vitamins and regulating blood clotting. Yet despite its importance, liver disease often develops silently, causing damage for years before symptoms appear.
This is why liver blood tests are so valuable. They can detect problems early, when treatment is most effective and before irreversible damage occurs. Understanding what these tests measure and what your results mean empowers you to protect this vital organ.
Why Liver Health Matters
The liver is central to virtually every metabolic process in your body:
When the liver is damaged, these functions become impaired, affecting your entire body.
The Silent Nature of Liver Disease
One of the most concerning aspects of liver disease is how quietly it develops. The liver has remarkable regenerative capacity and can continue functioning even when significantly damaged. This means symptoms often only appear once substantial harm has occurred.
Early liver disease typically has no symptoms. When symptoms do appear, they may include:
By the time these symptoms manifest, liver damage may already be advanced. This underscores the importance of blood tests for early detection.
Key Liver Blood Tests Explained
### Alanine Aminotransferase (ALT)
ALT is an enzyme found primarily in liver cells. When liver cells are damaged, ALT leaks into the bloodstream, causing elevated levels.
What elevated ALT may indicate:
ALT is considered more specific to the liver than AST, making it particularly useful for detecting liver problems.
### Aspartate Aminotransferase (AST)
AST is another enzyme released when liver cells are damaged. However, AST is also found in heart, muscle, and other tissues, so elevated levels are less specific to liver disease.
The AST:ALT ratio can provide diagnostic clues:
### Gamma-Glutamyl Transferase (GGT)
GGT is an enzyme found in liver, bile ducts, and other tissues. It is particularly sensitive to alcohol consumption and bile duct problems.
Elevated GGT may indicate:
### Alkaline Phosphatase (ALP)
ALP is found in the liver, bones, and other tissues. In the context of liver health, elevated ALP often suggests problems with bile ducts.
Elevated ALP may indicate:
### Bilirubin
Bilirubin is a yellow pigment produced when red blood cells break down. The liver processes bilirubin for excretion. Elevated levels cause jaundice. For detailed information, read our guide to understanding bilirubin tests.
Types of bilirubin:
Elevated bilirubin may indicate:
### Albumin
Albumin is a protein produced exclusively by the liver. Low levels indicate the liver is not functioning properly.
Low albumin may indicate:
### Prothrombin Time (PT) / INR
The liver produces clotting factors. When liver function is impaired, clotting takes longer, reflected in prolonged PT/INR.
Prolonged PT may indicate:
Common Liver Conditions Blood Tests Detect
### Non-Alcoholic Fatty Liver Disease (NAFLD)
NAFLD is the most common liver condition in the United Kingdom, affecting up to 30% of the population. It occurs when fat accumulates in the liver without significant alcohol consumption.
Blood test findings: Mildly elevated ALT and GGT, often with normal bilirubin and albumin in early stages.
### Alcoholic Liver Disease
Excessive alcohol consumption damages the liver progressively, from fatty liver to hepatitis to cirrhosis.
Blood test findings: Elevated AST (often higher than ALT), markedly elevated GGT, eventually abnormal bilirubin and albumin.
### Viral Hepatitis
Hepatitis B and C can cause chronic liver inflammation and damage.
Blood test findings: Elevated ALT and AST, with specific viral markers confirming the diagnosis.
### Cirrhosis
Cirrhosis represents advanced scarring of the liver from various causes.
Blood test findings: Elevated bilirubin, low albumin, prolonged PT/INR, and often low platelets.
Who Should Have Liver Function Tests?
Consider liver function testing if you:
For comprehensive health monitoring, liver tests are typically included in full health checks. Learn more about what's included in a comprehensive health check.
Protecting Your Liver
The good news is that many liver conditions are preventable or reversible with lifestyle changes:
Liver Health Testing in London
At Private Blood Tests London, we offer comprehensive liver function panels at our CQC-registered clinic in South Kensington. Our tests provide detailed information about your liver health, helping you detect problems early and take protective action.
Learn how to interpret your results with our guide to [decoding your liver function tests](/blog/decoding-your-liver-function-tests-lfts) and explore our [liver function test page](/liver-function-test).
Your liver works tirelessly for you. Return the favour by monitoring its health. Book your liver function test today.