Gamma Glutamyl Transferase (GGT) Test and Level Chart

Your annual blood tests are back and it shows something called GGT that you can’t quite grasp. Don’t worry about it since I am going to reveal all about gamma glutamyl transferase.

Gamma glutamyl transferase which is also known as GGT and glutamyl-transpeptidase shows the state of liver health. In case of inflammation of the liver, the GGT levels are going to rise.


GGT is an enzyme that is produced mainly by cells of the liver but also by the kidney and pancreas. Trace quantities of GGT are also found in the membrane of heart, spleen, bile ducts and seminal vessels.

Function Of GGT

The main function of gamma glutamyl transferase is to transfer amino acids between cells. Since it is synthesized mostly by the liver, any abnormality of liver functioning leads to raised levels of gamma glutamyl transferase (along with other liver enzymes such as aspartate aminotransferase and alanine aminotransferase).

If the liver is functioning normally then the GGT rates remain normal. But when the rates exceed normal value or are approaching the upper levels of tolerance, it is necessary to examine the liver in detail and find if there is hepatitis or cirrhosis of any type.

In summary, the rise of GGT is a warning sign of impending liver failure and a close watch has to be maintained if its values are out of normal range.

Why Doctors Prescribe GGT Assay

If you have pain in the upper right quadrant of your abdomen or nausea then it indicates that something might be wrong with your liver. The problem is usually more pronounced in those who consume alcohol or abuse painkillers.


The liver is the main chemical processing plant of the body. At any time there is about a pint of blood inside it being purified of toxins. Weighing about three pounds the liver also plays an important role in metabolism and secretes bile that helps with digestion.

It is a key component of the digestive system and can be affected by infections and cancer which can on many occasions be traced back to some type of abuse. An amazingly resilient organ, the liver can lose 75% of its mass to scarring and still function normally.

But the resilience also means that liver disease is silent, asymptomatic and one can only know about it when it is in an advanced stage. Gamma glutamyl transferase test is one of the principal tools that doctors use to prevent liver damage.

How Does GGT Test Take Place?

A GGT test is done on blood drawn from a vein. GGT levels fall after a meal and one needs to be on an eight hour fast for the test to happen. It is also preferable to avoid medication at that time (approximately 10 PM to 6 AM) and also beverages such as tea, coffee, and cocoa.


The normal value of GGT in blood:

  • Men – Less than 45 IU/L
  • Women – Less than 35 IU/L

The values mentioned above vary due to age and gender from 9 – 48 IU/L and have to be correlated with the laboratory performing the test.

Causes Of Raised GGT

  • Slight elevation of GGT is not a cause for concern. Those who have suffered jaundice and hepatitis will have elevated levels for about a year. Other than that the following reasons contribute to elevated GGT.
  • Common medications such as statins taken to lower cholesterol and long periods of antibiotic use (as happens with tuberculosis) could lead to increased GGT.
  • Prolonged use or off-prescription use of antibiotics is to be avoided. If one has to be on antibiotics then a GGT test has to be done once every four weeks and often more frequently.
  • Not only antibiotics but antidepressants such as Prozac may also cause liver malfunction and raise GGT.
  • It may be the warning sign of liver cancer or at least a benign tumor. This is why imaging such as ultrasound is necessary.
  • A diet that is rich in sugar may cause raised GGT. Sugar leads to obesity that is soon followed by insulin resistance. Fat accumulates in the liver and leads to abnormal test results.

Are you looking to lose weight?

If the above contributory causes are not present and yet GGT is high then it indicates a case of fatty liver or hepatic steatosis that can lead to scarring (dead regions of the liver where hepatocytes do not function). An advanced stage of fatty liver is cirrhosis which often proves to be fatal.


Raised GGT levels are followed by a full study of liver enzymes, and if needed an ultrasound and an MRI.

How To Reduce GGT Levels

No more alcohol

Cut down on alcohol consumption. Studies have found that even small amounts of alcohol may raise GGT levels for 24 hours. GGT levels return to baseline about a month after ceasing chronic drinking.

Eat lots of fruits and veggies

Consume plenty of fruits and vegetables. They contain antioxidants that are good at fighting what is known as oxidative stress. Normal metabolic activities result in the creation of hydroxyl ions known as free radicals inside the body. These are particularly toxic for the liver cells. Antioxidants reduce free radicals. At least one daily helping of fresh fruit or vegetable is needed for reducing GGT.

Drink more coffee

Studies in Japan have shown that consumption of caffeine reduces GGT. Unfortunately, tea does not contain enough caffeine for this purpose. However, caffeine creates problems of its own so take it with caution.

Avoid red meat

Red meat contains plenty of heme iron that raises GGT. If you are going to have meat, let it be chicken, turkey or tuna. White meat is far healthier than red meat.

Cod liver oil

A spoonful of cod liver oil is great for reducing GGT. Cod liver oil is high in Omega 3 fatty acids and acts well for liver detoxification.


A complete understanding of GGT and what its raised levels mean is not available yet. That is why the reference range of normal GGT is so broad.

I advise you to have a blood test once every few months to find if your liver is working fine. It is essential and a GGT test is an easy way for you to find out and nip any problems in the bud. There is no cause to be scared since liver problems are treated very easily and the organ can resume normal functioning in a month or two.


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