Gamma-Glutamyltransferase (GGT)

GGT is a sensitive marker of liver and bile-duct disease.

What it is

Gamma-glutamyltransferase, or GGT for short, is an enzyme found in many organs throughout your body, but it's particularly concentrated in the liver and bile ducts. Enzymes are like tiny helpers that speed up chemical reactions. GGT's main job is to help move other molecules around, particularly amino acids, which are the building blocks of proteins.

When your liver or bile ducts are damaged or inflamed, GGT can be released into your bloodstream. This is why measuring GGT levels in a blood test can give us clues about what's happening inside your liver and the tubes that carry bile from your liver to your gut. The typical reference range for GGT in the UK is between 10 and 71 units per litre (U/l), though this can vary slightly between laboratories.

Why it matters

Because GGT is released when there's stress or damage to the liver and bile ducts, it's considered a very sensitive marker. This means it can often be one of the first indicators that something might be wrong, even before other liver enzymes like ALT or AST rise.

Elevated GGT levels can suggest a problem with your liver or the bile ducts, which are the small tubes that transport bile from your liver to your small intestine to help with digestion. Bile is a fluid produced by the liver that aids in the digestion of fats. Issues with bile flow, known as cholestasis, can lead to a rise in GGT.

It's important to remember that GGT doesn't tell you what the specific problem is, only that there might be one. It's a piece of the puzzle that your doctor uses alongside your medical history, other symptoms, and potentially other blood tests to get a clearer picture of your health.

What can cause it to be high or low

A number of things can cause your GGT levels to be higher than the usual range.

Common causes for high GGT include:

• Alcohol consumption: Regular or heavy drinking is a very common cause of elevated GGT. The liver works hard to process alcohol, and this can lead to damage and increased GGT release.
• Liver diseases: Various liver conditions can lead to higher GGT. This includes fatty liver disease (where fat builds up in the liver), hepatitis (inflammation of the liver, which can be caused by viruses or other factors), and cirrhosis (scarring of the liver).
• Bile duct problems: Blockages in the bile ducts, perhaps due to gallstones or other issues, can cause GGT to rise as bile flow is impaired.
• Certain medications: Some medicines can affect liver function and lead to increased GGT levels. It's always important to let your doctor know about all the medications you are taking.
• Other medical conditions: Less commonly, conditions affecting other organs like the pancreas or heart, or even certain types of cancer, can sometimes be associated with higher GGT.

Low GGT levels are generally not a cause for concern and are rarely investigated. In some rare instances, very low GGT might be seen in people with certain deficiencies, but this is uncommon.

Lifestyle factors that may help

Given that alcohol consumption is a significant factor that can raise GGT, reducing or stopping alcohol intake is often a key lifestyle change that can help bring levels down. Your doctor can offer support and advice if you're looking to cut back on alcohol.

Maintaining a healthy weight and a balanced diet can also be beneficial for liver health. This often involves eating plenty of fruits, vegetables, and whole grains, and limiting processed foods, sugary drinks, and unhealthy fats. Regular physical activity is also a cornerstone of a healthy lifestyle that supports overall well-being, including liver function.

If certain medications are suspected of contributing to higher GGT, discussing alternatives with your GP might be an option. It's crucial never to stop or change any prescribed medication without professional medical advice.

Questions to discuss with your GP

If your GGT level has been found to be high, or if you have concerns about your liver health, here are some questions you might want to discuss with your GP:

• What might be causing my GGT level to be higher than the normal range?
• Are there any specific lifestyle changes that you would recommend for me, such as regarding diet or alcohol intake?
• Do my GGT results suggest I need further tests to investigate my liver or bile ducts?
• Could any of the medications or supplements I'm currently taking be affecting my GGT level?
• What are the next steps in managing my GGT level and ensuring my liver health?