GT Gamma Exam (GGT): what is it, high, low and what is it for

GT Gamma Exam (GGT): what is it, high, low and what is it for

What is GT range?

Gamma GT (gamma glutamyl transpeptidase or GGT) is the blood test that measures the amount of the enzyme gamma glutamyl transferase (GGT) in the body. This enzyme is mainly present in the liver and bile ducts, but it can also be found in cells in the kidneys, intestines, pancreas and spleen.

The test is especially useful to provide an analysis of the functioning of the liver and identify possible liver alterations, especially those related to alcohol consumption.

In some cases, it can detect bile duct obstruction.

When any of the organs that contain GGT does not work satisfactorily, the amount of enzyme in the blood may change, showing some functional failure of the body and allowing clinical investigation to identify the cause and, thus, carry out the treatment.

Because this enzyme is found in different parts of the body, the exam may not be able to specify in isolation which organ is having problems, which may require the request of additional tests.

In this article you will find the following information:

  1. How is done?
  2. When is it ordered?
  3. After all, what is alkaline phosphatase?
  4. GGT and alcoholism: what is the relationship?
  5. Pre-exam care
  6. Results
  7. GT high range
  8. GT low range
  9. Scratchs
  10. Common questions
  11. Complementary exams


How is done?

The gamma GT is a laboratory test performed by collecting blood by venipuncture of approximately 5mL, similar to the collection performed in the hemogram exam.

The test takes just a few minutes, does not cause major complications and does not require hospitalization.

Your results come out in approximately 24 hours.

When is it ordered?

In most cases, gamma GT is ordered in patients with suspected liver problems such as cirrhosis and hepatitis or excessive alcohol use.

However, the doctor may also recommend the test when identifying an elevated level of alkaline phosphatase, indicative of low vitamin D, suspected pancreatitis, among others.

Some indications of abnormal liver functions include:

  • Stools with lighter or whitish colors;
  • Dark urine;
  • Nausea accompanied by vomiting;
  • Pain or swelling in the abdomen region;
  • Sudden weight loss;
  • Swelling in legs or ankles;
  • Loss of appetite;
  • Itches;
  • Jaundice (yellowing of the skin or eyes);
  • Weakness;
  • Excessive fatigue;
  • Digestive bleeding.

After all, what is alkaline phosphatase?

Alkaline phosphatase (ALP) is also an enzyme that has a direct relationship with gamma GT and can be found in the liver and bones. Elevated levels of this enzyme may indicate disturbances in bone activity, as well as liver changes that affect the bile ducts.

For this reason, it is quite common for the alkaline phosphatase test to be complementary to the GGT test.

In cases of diseases of the bile ducts and liver, the levels of ALP and GGT will be high. However, in situations of high ALP and normal GGT, bone disease is likely.

GGT and alcoholism: what is the relationship?

Even in small amounts, alcohol consumption raises blood levels of the enzyme GGT. For this reason, the gamma GT test can be used to screen or monitor alcohol use/abuse in patients undergoing treatment for alcoholic hepatitis and alcoholism.

It is noteworthy that in about 75% of chronic drinkers, the enzyme level will be high.

Pre-exam care

Some guidelines before taking the exam are:

  • Stop drinking alcohol or cigarettes 24 hours before the exam;
  • Not having performed a liver biopsy in the last 5 days;
  • Fasting for at least 8 hours (confirmation with the laboratory that will perform the procedure is required, as your need may vary).

The physician may also request the suspension of some medications that tend to change the test result, such as:

  • Hidantal ,
  • Phenytoin,
  • Carbamazepine,
  • Non-steroidal anti-inflammatory drugs,
  • Antibiotics,
  • Antiallergics,
  • Antifungals,
  • Antidepressants,
  • Contraceptives,
  • Testosterone-based drugs.

Therefore, it is very important to inform the health professional about the medications used.


As the GT gamma reference values may vary depending on the laboratory, it is essential to present the results for analysis with the physician. Generally, values considered normal are between 8 to 61 U/L (men) and 5 to 36 U/L (women).

GT high range

Elevated GGT suggests that some disease or condition is damaging the liver, and generally, the higher this result, the greater the damage. Factors that justify the discharge include:

  • Viral hepatitis (hepatitis A, hepatitis B or hepatitis C);
  • Drug or alcoholic hepatitis;
  • Toxic hepatitis;
  • Autoimmune hepatitis;
  • Abuse of alcoholic beverages, cigarettes, medications or other drugs;
  • Cirrhosis;
  • Obstruction of the bile ducts;
  • Use of some medications;
  • Diabetes;
  • Liver steatosis (fatty liver);
  • Liver inflammations;
  • Acute myocardial infarction (approximately 4 to 10 days after the episode);
  • Hyperthyroidism etc.

How to decrease?

The main factor for reducing the GT range is identifying the cause of this increase, such as cutting or reducing alcohol consumption, replacing medication and treating the causing diseases.

The professionals responsible for treating the clinical condition are the gastroenterologist or hepatologist. In cases of viral hepatitis, there may also be a need for follow-up by an infectologist.

Care to avoid GGT elevation

Paying attention to simple habits to prevent GT gamma elevation can also help prevent other health problems. Care includes:

  • Physical activity practice;
  • Balanced diet, consuming all food groups (protein, fiber, carbohydrates);
  • Avoid the consumption of alcoholic beverages and cigarettes;
  • Introduce foods rich in omega 3 and anti-inflammatory drugs in the diet;
  • Reduce your consumption of fats and sugars.

GT low range

A low value as a result of the GT gamma indicates unlikely liver problems and alcohol consumption. However, if associated with an elevated alkaline phosphatase level, it may be indicative of vitamin D deficiency, Paget’s disease or bone disease.


As it involves blood collection, the risks of the GT gamma test are few, and may include:

  • Bleeding at the syringe insertion site (needle);
  • Dizziness;
  • Drop in blood pressure (hypotension);
  • Fainting;
  • Infection (rare).

Common questions

Does high GGT always show symptoms?

The increase in GGT in many cases can be asymptomatic, that is, it does not have any symptoms. This condition can be temporary, as in the case of alcohol consumption or medication use.

If other enzymes do not show changes, the doctor may order a new test to confirm the result and perform an analysis of the temporary increase or the cause of the elevation.

Does the GGT level return to normal when you stop drinking alcohol?

Abstaining from alcohol will cause the GGT level to return to normal over time. However, in cases of alcoholism, this change can take weeks or months. This will also allow your liver function to improve.

Complementary exams

There are cases in which some additional exams are needed in order to identify the cause of the increase in GT gamma rates:

  • Blood count: performs the analysis of blood parameters;
  • Tests to identify liver and biliary functions: the most common include tests for alkaline phosphatase, bilirubin alanine transaminase (ALT), lactic dehydrogenase, albumin, prothrombin time;
  • Type 1 urine test: analyzes indicators of glucose, proteins, leukocytes and red blood cells, which indicate the functionality of the kidneys;
  • Uroculture: just like the type 1 urine test, it assesses the functioning of the kidneys;
  • CA 19-9 tumor marker: used in patients with suspected pancreatic cancer or other conditions such as pancreatitis;
  • Amylase: responsible for identifying pancreatitis;
  • Colonoscopy: checks for cancer in the small and large intestines;
  • Ultrasound or tomography: exercises the study of spleen enlargement.

Gamma GT is able to identify liver problems. Once you get the results of the exam, consult your doctor so that he can perform the interpretation and, if necessary, indicate the best treatment.