All about liver function tests (LFTs)

Liver tests, often called liver function tests (LFTs), are common blood tests used to check how well your liver is working. The liver plays an essential role in filtering toxins, processing nutrients and supporting digestion. When a test result comes back abnormal, it can cause worry, but it does not always mean there is serious liver disease.

What do liver tests measure?

Liver tests usually check different enzymes and proteins in the blood. These include:

ALT (alanine aminotransferase) and AST (aspartate aminotransferase), which are enzymes found in liver cells. High levels may suggest liver inflammation or damage.
ALP (alkaline phosphatase), which may be raised if there is a problem with the bile ducts or liver.
GGT (gamma-glutamyl transferase), often used to check for bile flow problems or alcohol-related liver changes.
Bilirubin, a yellow pigment made when red blood cells break down. High levels cause jaundice.
Albumin and clotting tests, which reflect how well the liver is producing important proteins.

What causes abnormal liver test results?

Abnormal results can be caused by many conditions, and not all are serious. Common causes include:

Fatty liver disease, linked to weight gain or diabetes
Alcohol-related liver irritation
Viral infections like hepatitis A, B or C
Side effects of medicines or herbal supplements
Gallstones or problems with bile ducts
Autoimmune or genetic liver conditions

Sometimes, mild changes in liver tests are temporary and return to normal without treatment.

Do abnormal liver tests always mean liver disease?

Not always. Liver tests show that the liver is under stress or not working normally, but they do not give a diagnosis on their own. Your doctor may repeat the test, ask about symptoms or arrange more investigations to understand the cause.

What symptoms should I look out for?

Many people with abnormal liver tests do not have symptoms. However, some may notice:

yellowing of the skin or eyes
tiredness or low energy
nausea or loss of appetite
darker urine or pale stools
pain or discomfort under the ribs on the right side

What happens next if results are abnormal?

Your doctor will decide the next steps depending on how high the levels are and your medical history. This may include:

repeating the blood test after a few weeks
arranging an ultrasound scan
checking for viruses like hepatitis
reviewing medicines, alcohol intake or lifestyle factors

How can I protect my liver health?

Maintain a healthy weight via a balanced diet, and regular exercise
Limit alcohol intake. If advised, avoid it altogether
Take medicines only as prescribed and avoid unnecessary supplements
Get vaccinated against hepatitis A and B if you are at risk
Attend regular monitoring if you already have a liver condition