GGT blood test: what it measures and what your result means

Medically reviewed by Dr Lebeth Jacob · 21 October 2026

Quick answer: GGT (gamma-glutamyl transferase, or gamma-GT) is an enzyme found mainly in the liver. It's one of the most sensitive markers of liver strain, and it often rises with regular drinking, fatty liver or a problem with the bile ducts. A raised GGT doesn't say what's causing it on its own, so it's read alongside other liver tests.

What is GGT?

GGT is an enzyme found in the liver, especially in the bile ducts, and in smaller amounts in the kidneys and pancreas. When the liver is under strain, or bile isn't flowing freely, more GGT gets into the blood.

GGT is very sensitive, so it can rise before other liver tests change. That makes it useful as an early warning, but it also means it can be raised for fairly common reasons.

Why is GGT tested?

  • As part of a routine liver function test
  • You drink alcohol regularly, or want to see the effect of cutting down
  • Your ALP is raised, and a doctor wants to know if it's coming from the liver or bone
  • You're overweight or have type 2 diabetes, which raise the risk of fatty liver
  • You take medicines that can affect the liver

What does a high GGT result mean?

A raised GGT means something is affecting your liver or bile ducts. Common reasons are:

  • Regular drinking, even at levels some people think of as moderate
  • Fatty liver, linked to extra weight and diabetes
  • Gallstones or other causes of a blocked bile duct
  • Some medicines, including some for epilepsy
  • Smoking
  • Hepatitis and other liver conditions

If ALP is also raised, the cause is more likely to be in the liver or bile ducts. If GGT is the only raised result, alcohol and fatty liver are the most common reasons.

What does a low GGT result mean?

A low GGT is normal and not a concern.

What can affect your result?

  • Alcohol in the weeks before the test can raise GGT, not just the day before
  • Some medicines, including some epilepsy medicines, raise it
  • Smoking raises it
  • After cutting down on alcohol, GGT usually falls over a few weeks

When to see a GP

Your results report shows the laboratory's normal range and flags any result outside it. Speak to your GP if:

  • Your GGT is flagged high, especially if other liver tests are also raised
  • It stays high after you've cut down on alcohol
  • You're worried about how much you drink. Your GP can help, and NHS alcohol support lists free services.

Get medical help the same day (GP or NHS 111) if your skin or the whites of your eyes turn yellow, or you have dark urine and pale stools.

How we test GGT

You can have GGT tested with a blood sample taken at one of our 250+ partner clinics, or with a finger-prick kit at home. Samples are analysed by a UKAS-accredited laboratory. Results are usually ready in 3–5 working days, with a doctor's comments on every result.

Tests that include GGT

Prices for in-clinic tests include your appointment. Compare every test with GGT in the biomarker explorer

Frequently asked questions

What level of GGT is dangerous?

There is no single dangerous number. A mildly raised GGT is common and often caused by alcohol or fatty liver. A very high GGT, or one that's raised with other abnormal liver tests, should be looked into by a GP.

Does a high GGT mean cancer?

Usually not. Most raised GGT results are caused by alcohol, fatty liver, gallstones or medicines. Cancers affecting the liver can raise it, but they're a much less common cause.

How can I lower my GGT?

Cut down on alcohol, or stop for a few weeks, and then retest. Losing extra weight, stopping smoking and being active help too. If it's still raised, see your GP.

How quickly does GGT go down after stopping drinking?

It usually falls over a few weeks. A repeat test four to six weeks after cutting down shows how much it has changed.

Why is my GGT high when my other liver tests are normal?

GGT is more sensitive than the other liver tests, so it's often the first to rise. Alcohol, fatty liver, smoking and some medicines are the usual reasons.