GGT is an enzyme produced in liver cells and found mostly in the kidneys in the body. Apart from the liver and kidneys, it is found in cell membranes in other tissues such as the pancreas, intestine, spleen, heart, brain, and seminal vesicles. It activates the transport of amino acids and many other protein residues in cells.

GGT test

GGT is an enzyme produced in liver cells and found mostly in the kidneys in the body. Apart from the liver and kidneys, it is found in cell membranes in other tissues such as the pancreas, intestine, spleen, heart, brain, and seminal vesicles. It activates the transport of amino acids and many other protein residues in cells. While GGT is cleared and excreted by the liver, a small amount is excreted by the kidneys.

Normal values of GGT in blood are accepted as 0-30 IU/L. While 6-7 times the levels of adults can be seen in infants, it has been stated that it can be 25% higher in adult men than in women.



Because GGT is liver specific, it is a test used especially in alcohol-related liver diseases. At the same time, high GGT levels can be seen in many diseases such as diabetes, obesity, chronic obstructive pulmonary disease, some malignancies and congestive heart failure. GGT may also be increased in the use of phenytoin, carbamazepine and barbiturates.

In patients with high ALP levels, GGT levels are checked to evaluate whether the source of the problem is the liver. GGT elevation is specific in active liver damage and biliary tract obstructions.

GGT is also abundant in the epithelium of the bile ducts and its level is quite high in biliary tract obstructions.

The patient’s history of drug or alcohol use is questioned in patients with only elevated GGT levels in blood tests. If patients using alcohol or a drug that can increase GGT levels do not drink alcohol for 6 months, GGT levels are expected to return to normal. If it returns to normal, other imaging and biopsy procedures related to the liver can be applied.



In patients with elevated GGT in blood tests, as well as in other liver function tests, liver diseases are considered first, and then an evaluation is made in terms of other metabolic diseases. The treatment process of diseases such as diabetes, obesity or hyperlipidemia is monitored for 6 months. If there is still no improvement in GGT levels in the repeat control, further liver tests can be evaluated.

GGT can sometimes be used to monitor and evaluate the effects of kidney diseases or some diseases such as diabetes on the kidneys. Because ischemia in kidney cells can also cause elevations in GGT levels.

Sudden GGT elevations usually indicate hepatobiliary obstruction and obstructive jaundice. Sometimes, tumor metastases to the liver and sudden GGT elevations can be seen as a result of these metastases causing obstruction.

The most common possible causes of GGT elevation are:

  • Liver-related causes
  • Cirrhosis
  • Hepatitis (acute and chronic)
  • Liver metastasis and cancer
  • Cholestasis
  • Liver disease due to alcohol use
  • Primary biliary cirrhosis and sclerosing cholangitis

Extra reasons for GGT level rise include:

  • Pancreatitis
  • Prostate cancer and diseases
  • Brain tumors
  • Breast and lung cancer
  • Systemic lupus erythematosus
  • Alcohol addiction
  • Congestive heart failure and chronic coronary artery disease
  • Medicines
    • Paracetamol
    • Carbamazepine
    • Phenytoin
    • Phenobarbital

Low GGT:

Some chemicals such as birth control pills or clofibrate can cause low GGT. The lack of expected elevation in GGT levels in some patients who use birth control pills despite having liver diseases may be a matter to be considered.