My Liver Tests Came Back High: What Does It Mean?

Finding a raised ALT, AST, GGT or ALP on a blood test often leads people to worry: “Is there something seriously wrong with my liver?”

But one of these tests being high does not on its own make the diagnosis of any particular disease.

A raised liver test is not a diagnosis but a laboratory finding whose cause needs looking into.

The assessment weighs together which test has risen, how far it has risen, the state of the other tests, how long the rise has been going on and the patient’s symptoms.

Do “liver function tests” really show the liver’s function?

In everyday speech ALT, AST, GGT and ALP are often called “liver function tests”. Technically that is not quite right.

ALT, AST, GGT and ALP are enzymes that give information mainly about liver cell damage or changes involving the bile ducts.

When the liver’s synthetic function is being assessed, other tests matter in particular:

• Albumin
• INR/prothrombin time

Bilirubin, meanwhile, gives information about the liver’s processing of bilirubin and its removal through the bile.

What does a raised ALT mean?

ALT (alanine aminotransferase) is an enzyme found in abundance in liver cells. When liver cells are damaged, ALT passes into the blood and can rise.

Common causes of a raised ALT include:

• Metabolic fatty liver disease
• Viral hepatitis
• Liver damage from medicines or some herbal products
• Alcohol-related liver disease
• Autoimmune and metabolic liver diseases

But none of these can be diagnosed from a raised ALT alone.

The higher the ALT, the more damaged the liver?

Not always.

A raised ALT can give information about whether liver cell damage is present; but it is not related one-to-one with the severity of the disease or the amount of fibrosis in the liver. In some advanced chronic liver diseases, for instance, ALT can be only mildly raised or even normal.

A normal ALT does not always mean a completely healthy liver either.

What does a raised AST mean?

AST (aspartate aminotransferase) is found in the liver, but it is not as specific to the liver as ALT.

AST is also found in:

• Muscle
• The heart
• Red blood cells
• Some other tissues

So a raised AST does not always come from the liver.

Can exercise raise AST?

Yes. Intense exercise or muscle damage can raise AST. In that case assessing muscle enzymes such as CK (creatine kinase) can help.

So “high AST = definitely liver disease” is not correct.

Why are AST and ALT assessed together?

Assessing AST and ALT together can give some clues about the possible causes of liver damage. In some conditions ALT rises more markedly, in others AST. In alcohol-related liver disease, for instance, a pattern where AST is higher than ALT can be seen.

What does a raised GGT mean?

GGT (gamma-glutamyl transferase) is an enzyme that can rise particularly in conditions involving the liver and the bile ducts.

A raised GGT can be seen in:

• Diseases of the bile ducts
• Fatty liver
• Alcohol use
• The use of some medicines
• Various liver diseases

Does a raised GGT mean I drink alcohol?

No. This is quite a common misreading.

Alcohol use can raise GGT; but alcohol is not the only cause of a raised GGT. Fatty liver, diseases of the bile ducts and some medicines can raise it too.

A high GGT cannot be read as “this person drinks”.

What does a raised ALP mean?

ALP (alkaline phosphatase) is an enzyme found particularly in the bile ducts, in bone and in some other tissues.

A raised ALP related to the liver and bile ducts can be seen with:

• Stones in the bile ducts
• Blockage of the bile ducts
• Narrowing of the bile ducts
• Cholestatic liver diseases
• Some conditions affecting the liver

But ALP has an important feature: it does not come only from the liver. It can also be high in bone disease, during periods of growth and in some physiological states.

How is it known whether a raised ALP comes from the liver or from bone?

GGT can be quite helpful in making this distinction.

• ALP ↑ + GGT ↑ — supports the likelihood that the rise comes from the hepatobiliary system, that is from the liver or the bile ducts.
• ALP ↑ + normal GGT — causes arising from bone should be considered too.

Where needed, ALP isoenzymes or other tests can be used.

Is a raised ALT/AST the same as a raised ALP/GGT?

No. This distinction is one of the most important points in assessing liver tests.

If ALT and AST are more markedly raised

This is called a hepatocellular pattern. In other words, the liver cells being affected comes to the fore. It can be seen in:

• Viral hepatitis
• Metabolic fatty liver disease
• Liver damage from medicines
• Autoimmune hepatitis

If ALP and GGT are more markedly raised

This can suggest a cholestatic pattern. Conditions involving the formation or flow of bile come to the fore. Causes that may be looked into include:

• Stones in the bile ducts
• Blockage of the bile ducts
• Narrowing of the bile ducts
• Primary biliary cholangitis (PBC)
• Primary sclerosing cholangitis (PSC)
• Some medicines

If both groups have risen together

A mixed pattern can be seen. Here both hepatocellular and cholestatic features may be present together.

What does it mean if bilirubin is high too?

A raised bilirubin accompanying a raised ALT, AST, ALP or GGT matters particularly.

The patient may have:

• Yellowing of the eyes and skin
• Dark urine
• Pale stools
• Itching

Where ALP, GGT and direct bilirubin are raised together in particular, the bile ducts may need assessing.

Does fatty liver raise these tests?

Yes.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is one of the common causes of a mild or moderate rise in liver enzymes. It is common particularly in people with:

• Excess weight
• Fat around the waist
• Diabetes
• Insulin resistance
• Raised triglycerides
• Metabolic syndrome

But: normal liver enzymes do not entirely rule out fatty liver disease.

Can medicines raise liver tests?

Yes. A great many medicines can affect liver tests.

In addition, the following can cause liver damage:

• Herbal products
• Slimming products
• Sports supplements
• Dietary supplements

This is why it matters to tell your doctor about everything you take.

Is viral hepatitis looked for?

Depending on the clinical picture, investigation for viral hepatitis — hepatitis B and hepatitis C above all — may be needed. For example:

• HBsAg
• Anti-HBc
• Anti-HCV

and, where needed, further viral tests may be used. Which tests are needed is decided from the person’s clinical situation.

Can there be rarer causes?

Yes. In people whose liver tests stay raised over a long period, or whose rise has no explanation, less common conditions may be looked into in suitable patients:

• Autoimmune hepatitis
• Primary biliary cholangitis
• Primary sclerosing cholangitis
• Haemochromatosis
• Wilson’s disease
• Alpha-1 antitrypsin deficiency

Which tests may be needed?

Not everyone has the same tests. Where your doctor thinks it necessary, they may request:

• ALT, AST, ALP, GGT
• Total and direct bilirubin
• Albumin
• INR
• Full blood count
• Viral hepatitis tests
• Iron and ferritin
• Autoimmune tests
• Metabolic tests

For imaging, abdominal ultrasound is usually one of the first methods. If needed, elastography, CT, MRI/MRCP, EUS or other investigations may be used.

Does it matter if the tests are only slightly high?

Mild rises can be temporary. Results can be affected by:

• A recent illness
• Some medicines
• Intense exercise
• Alcohol
• Metabolic factors

But persistent or recurring rises in particular should be investigated. Leaving them unchecked for years on the grounds that “it is a bit high, it does not matter” is not right.

Does the test need repeating?

In some patients, yes. Depending on the clinical picture your doctor may want the tests repeated after a certain interval.

Your previous results are particularly valuable. For example:

• ALT 35 → 38 → 36
• ALT 45 → 110 → 260

are not judged in the same way. The change over time can give important information.

When is urgent assessment needed?

Assessment is needed without delay if a raised liver test is accompanied by any of the following:

• Jaundice together with fever or shivering
• Jaundice together with severe right upper abdominal pain
• Confusion or excessive sleepiness
• Severe and persistent vomiting
• Vomiting blood or black stools
• Rapidly increasing swelling of the abdomen
• A rapidly worsening general condition

What should you do if your liver tests are high?

1. Do not panic. A mildly raised enzyme can have many causes.
2. Do not look at a single enzyme. Weighing ALT, AST, GGT, ALP and bilirubin together is more meaningful.
3. Find your previous results. Whether the rise is new or long-standing matters.
4. Tell your doctor about everything you take. Herbal products and supplements as well as prescribed medicines.
5. Consider your metabolic risks. Weight, diabetes, blood lipids and fatty liver matter.
6. If the cause cannot be explained, it should be investigated. Viral, autoimmune, metabolic and biliary causes are examined where needed.

Remember

• ALT Is an important enzyme for liver cell damage.
• AST Can come from muscle and other tissues as well as the liver.
• GGT Relates to the liver and bile ducts; a rise does not mean alcohol alone.
• ALP Can come from the bile ducts or from bone.
• Bilirubin Matters particularly in assessing jaundice and the flow of bile.
• ALT/AST ↑ Can suggest a hepatocellular pattern.
• ALP/GGT ↑ Can suggest a cholestatic pattern.
• A raised liver test Is not on its own a diagnosis of cirrhosis, hepatitis or cancer.

The most important message

With liver tests, what matters is less any single number than the pattern the tests make together.

When the ALT, AST, GGT, ALP and bilirubin results are weighed together, important clues emerge as to whether the rise may be coming from the liver cells, from the bile ducts, or from a source outside the liver altogether.