GGT blood test: normal range and what a high GGT means

A GGT blood test measures gamma-glutamyl transferase, an enzyme that the blood picks up mainly from the liver and bile ducts. It is a sensitive marker and not a specific one: it rises with alcohol, with some medicines, with excess weight and with almost any liver or bile duct problem. Its other job is to tell a doctor whether a high ALP comes from the liver or from bone.

What GGT measures

GGT is an enzyme found mainly in kidney, liver and pancreas cells, with small amounts elsewhere. The kidney holds the most, but the GGT circulating in blood comes mainly from the liver and bile ducts. Bone holds none, which is what makes GGT useful beside ALP.

GGT also responds to things other than liver injury. Some medicines, such as the anti-seizure drugs phenytoin and phenobarbital, prompt the liver to make more of it, and it is raised in most heavy drinkers. So a raised GGT is a prompt to ask why, more than an answer in itself.

GGT normal range

GGT is reported in units per litre (U/L, also written IU/L). Men run higher than women, and populations differ so much that an international reference study concluded a single worldwide range is unlikely:

Reference	Men	Women
Mayo Clinic Laboratories, age 18 and over	8 to 61 U/L	5 to 36 U/L
IFCC multicentre reference study, adults	12 to 68 U/L	6 to 40 U/L

Children have their own ranges, lower than adults' from the age of one. Read your result against the range printed on your own report.

What a high GGT usually points to

The British Society of Gastroenterology names obesity, excess alcohol and medicines as the most common reasons for a raised GGT. Beyond those:

• Bile duct problems. GGT reaches its highest levels, often 5 to 30 times normal, when bile flow is blocked inside or outside the liver, and it rises earlier than ALP.
• Liver disease of almost any kind, including fatty liver (MASLD) and viral hepatitis, where the rise is usually more modest: 2 to 5 times normal in infectious hepatitis.
• Other conditions. MedlinePlus lists pancreatitis, diabetes and heart failure.

Read with ALP, GGT answers a specific question. High ALP with high GGT points to the liver; high ALP with a normal GGT points to bone.

A raised GGT also says something about longer-term health. British guidance notes that, although it is not specific, GGT is one of the strongest signals of long-term liver risk. In large population studies, higher GGT, even within the normal range, went with a higher later risk of type 2 diabetes and of cardiovascular disease. These are associations across populations, not a forecast for one person, and they are part of why GGT sits well beside HbA1c and fasting insulin; our article on reading HbA1c, glucose and insulin together covers those.

What a doctor typically looks at next

A doctor usually starts with alcohol, current and past, then medicines and supplements, weight and blood sugar, and reads GGT with ALP, ALT, AST and bilirubin. In British guidance, a GGT above 100 U/L in someone drinking at hazardous levels is a reason to assess the liver for scarring. When GGT is raised on its own in someone who drinks little, weight, metabolic health and medicines are the usual places to look.

A low GGT

MedlinePlus notes that a low or normal GGT makes liver disease less likely.

What moves GGT

• Alcohol. Drinking raises GGT, and most people with alcohol use disorder have a high GGT. Mayo Clinic Laboratories notes rises after alcoholic drinks.
• Medicines and supplements. Mayo advises that a raised GGT should not be read as liver disease until drug use is ruled out.
• Weight. Across 17 studies, people with metabolic syndrome had GGT about 11 U/L higher on average.
• Smoking, which MedlinePlus lists among the things that affect results.
• Meals. GGT falls after eating, one reason labs may ask for a fasting sample.
• Exercise. GGT stayed normal after a hard weightlifting session that sharply raised ALT and AST.
• Pregnancy. Mayo notes that GGT stays normal in healthy pregnancy, unlike ALP.
• Ramadan fasting. In a 2021 review, the two small studies that measured GGT across Ramadan (46 people in total) found a moderate fall.
• The sample. GGT is robust: in one laboratory study, burst red cells did not distort it even when haemolysis was severe.

Preparing for the test

GGT drops after meals, so labs may ask you to fast, and it is usually drawn with tests that need fasting anyway. Tell the person taking the sample about medicines and supplements, and mention recent alcohol, since drinking in the days before can raise GGT. MedlinePlus advises against stopping any medicine unless your doctor tells you to.

How Clare's panel handles GGT

Clare's panel includes GGT, measured by the lab. It is drawn with ALP, so the liver-or-bone question can be answered from the same sample, and with ALT and AST, so a doctor can see whether GGT is rising alone or as part of a wider liver pattern.

Price

GGT is usually sold within a liver function test. When we read public prices on 11 October 2026, a liver function test cost from 89 to 1,100 at six UAE providers. The top figure was a wider package that adds a hepatitis B test; the five standard liver panels ran from 89 to 199. Most listings did not say whether VAT was included, and home collection can add a fee: one lab charged for it on smaller orders.

Related tests

GGT is one part of the Liver function test. Read it with Alkaline Phosphatase (ALP), which GGT helps place as liver or bone; Alanine Aminotransferase (ALT), the liver cell enzyme; and Hemoglobin A1c (HbA1c), for the metabolic side GGT is linked with.

Why GGT means more over time

Because GGT rises with alcohol and with weight, it is one of the liver markers most likely to move when habits change. A GGT that comes down between two tests after a change in drinking or weight is one way to see that change in the blood. One that keeps climbing, especially beside ALP, is worth raising with a doctor. Single readings are noisy enough, from meals, medicines and a recent drink, that the trend is the more useful number. When Clare opens, each member's results will sit in one health account, with each marker's trend over time.

Clare is opening with a waitlist at clare.health.