It is likely that on more than one occasion we have had some blood test or other, either to check the values of elements such as cholesterol, triglycerides or blood sugar or to the presentation of some kind of symptoms that suggest the existence of a particular disease (in which case a more specific analysis is made).

Thanks to them we can detect very diverse pathologies, observing for example altered levels of lipids, leukocytes or even some enzymes. An example of this occurs when we have the gamma glutamyl transferase or high GGT , an indicator of the existence of possible damage to organs such as the liver. Throughout this article we will make a brief dissertation regarding what it is and what it can imply to have high GGT, as well as some conditions that can provoke it.

What is the GGT and when do we start having it high?

It is called gamma glutamyl transferase or GGT , an important enzyme present in several organs of the human body , with special preponderance in the liver (being the organ in which it is found in greater proportion), the heart and the gallbladder but also being present in others such as the kidneys or the brain.

The main function of this enzyme is to metabolize the main antioxidant that our body manufactures, glutathione , as well as to transfer it to other amino acids. It thus contributes, among other things, to maintaining cellular health and homeostasis and to strengthening the immune system. As we have said, it is part of several organs, and certain levels of this enzyme can be found in the blood.

Generally, values between 0-30 or 7-50 units per liter of blood are considered normal. Above these values, this enzyme is considered to be at a high level, which indicates the presence of damage to one of the organs mentioned above, basically the first three, the most likely being the liver. The increase is usually due to a filtration of the enzyme through damage or injury to these organs .

How are their levels evaluated and assessed?

While this may not seem to generate symptoms at first, it is common for those who generate high levels of GGT to produce different alterations.

These can vary greatly based on the causes, but the most common are the presence of jaundice or yellowish colouring of the eyes and skin, weakness, changes in the colouring of urine and faeces (the first usually darkens and the second lightens), sudden drop in appetite, itching of the skin, gastrointestinal discomfort and pain or nausea and vomiting, these being indicators of the presence of damage that make it advisable to carry out the relevant analysis.

The assessment of GGT levels will be done through a blood test , usually after a period of time without eating or drinking. It is no more dangerous than other blood tests, and once in possession of the sample the test is relatively quick to perform.

However, it should be noted that having high GGT does not have a unique identifiable cause, and its levels do not serve as a precise indicator of where the damage may be. This is why it is often necessary to perform complementary analyses that evaluate other enzymes.

Possible causes of high GGT

As we have just commented, there are multiple reasons that can cause us to have high GGT, often requiring the analysis of the levels of other substances to determine the specific cause of this alteration. Among the most common causes of its elevation above normal, we can highlight the following.

1. Hepatitis

The different types of hepatitis, which are inflammations of the liver which can come from causes as varied as infection by a virus or food poisoning, have also been associated with the presence of alterations which facilitate the GGT filtering into the blood, generating an increase in its levels.

2. Alcoholism and alcoholic cirrhosis

The excessive consumption of alcohol and its consequences on the liver are one of the possible causes that can generate that we have a high GGT, due to the existence of lesions through which the enzyme goes out to the blood flow. An example is found in alcoholic liver cirrhosis, in which the liver has degenerated in such a way that presents a great deal of scarring and a very diminished functioning of the organ .

3. Diabetes mellitus

Another condition that can lead to elevated GGT levels is diabetes mellitus, regardless of whether it is insulin-dependent or not. The mentioned increase usually occurs mainly in those people who do not follow the treatment or medical recommendations, being habitual in such cases that lesions in the liver can appear. Fortunately, good control of blood glucose prevents the GGT from increasing .

4. Liver cysts and tumors

One reason that can also cause a high level of GGT in the blood is the presence of liver damage from cysts and tumours, either because we are dealing with a tumour that appears in the organ or because, despite being in another place, it generates pressure or compression in/of the organ.

5. Drug consumption

An increase in GGT is not always due to illness, but can also result from the effects of the consumption of certain drugs or substances. Among these, some antibiotics or drugs to treat epilepsy may be highlighted. Another type of drug that can generate a high GGT is oral contraceptives. In addition, substances such as alcohol or phenobarbital (a barbiturate, anxiolytic and sedative) also generate a high GGT.

6. Blockage of vesicular channels or blood hypoperfusion

In addition to the above, there are other diseases and injuries that can cause the emission of GGT into the blood to be excessive, the causes of which can be found in problems in the communication of the gallbladder with the liver or the absence of sufficient blood reaching the area. It may also result from internal bleeding.

7. Heart failure

Especially frequent in the elderly population, the presence of heart problems such as heart failure also generates an elevation of the GGT, in this case not so much derived from the liver but from the main organ of the cardiovascular system.

Bibliographic references:

  • Chernecky, C.C. & Berger, B.J. (2013). Gamma-glutamyltranspeptidase (GGTP) – blood. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. St Louis, MO: Elsevier Saunders:559-560.
  • American Accreditation HealthCare Commission (2017). Gamma-glutamyl transferase (GCT) blood test. MedlinePlus [Online]. Available at: https://medlineplus.gov/spanish/ency/article/003458.htm.