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Normal (GGT) Gamma Glutamyltransferase level in the blood

Blood test
Normal (GGT) Gamma Glutamyltransferase level in the blood
Last update: 26/03/2020

What is the normal level of GGT in the blood?

Adult men: 8 - 55 U/L
Adult women: 5 - 38 U/L
0 to 6 months old: 12 - 122 U/L
6 months to 1 year old: 1 - 39 U/L
1 year to 12 years old: 3 - 22 U/L
13 - 18 years old: 2 - 42 U/L

In the International System of Units (SI), the GGT in the blood is measured in ukat/l. The normal GGT levels in the blood in the SI are:

Adult men: 0.13 - 0.92 ukat/L
Adult women: 0.08 - 0.63 ukat/L
0 to 6 months old: 0.2 - 2 ukat/L
6 months to 1 year old: 0.02 - 0.65 ukat/L
1 year to 12 years old: 0.05 - 0.37 ukat/L
13 - 18 years old: 0.03 - 0.7 ukat/L

Why normal levels can differ across different labs?

Each laboratory must establish its own normal ranges for the GGT in the blood. These ranges depend on the makeup of the local population, the technologies used and the accuracy of the measurement. There may be also slight differences in the normal levels according to age, gender, race or ethnic origin, geographic region, diet, type of sample and other relevant status.

Your doctor will study the results along with your medical record, screenings, physical condition, symptoms and any other relevant information about your situation.

What is the role of the GGT?

The GGT (Gamma-glutamyltransferase) is an enzyme involved in the amino acid transport and in the metabolism of glutathione. Glutathione is an antioxidant that prevents the cell damage induced by free radicals and heavy metals.

The GGT is mainly present in the body in the:

  • Liver
  • Bile duct

The GGT is also found in small amounts in the kidneys, the heart, the spleen, the intestine, the brain and the prostate. Its presence in the prostate explains why normal ranges are a bit higher in men than in women.

What is the GGT blood test used for?

The GGT (Gamma GT) blood test is used for multiple reasons:

  • To detect a liver disease
  • To detect a bile duct obstruction
  • As an indicator for chronically heavy alcohol consumption
  • To explain an alkaline phosphatase (ALP) increase

If there is a bile duct obstruction, the GGT level will be higher than normal. The GGT test is also closely related to liver damage produced by alcohol intake. The GGT level will be high in case of alcohol abuse. The GGT level in the blood will be higher than normal in about 75% of people who drink too much alcohol.

If the alkaline phosphatase (ALP) is high and the GGT is also high a liver damage or a bile duct obstruction is suspected. If alkaline phosphatase (ALP) is high but the GGT is normal it may indicate a bone disease.

If the GGT level in the blood is lower than normal it could be due to magnesium deficiency.

Where can I find more information about GGT in the blood?

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Which values are considered a normal GGT level in the blood?

The following values are considered to be normal values:

IMPORTANT: These levels are expressed in U/L. They are an example of a healthy man of about 45 years old with no known disease and not taking any medication. The ranges can be different depending on the laboratory or on your personal circumstances.

GGT Gamma Glutamyltransferase
8 U/L9 U/L10 U/L11 U/L12 U/L13 U/L14 U/L15 U/L
16 U/L17 U/L18 U/L19 U/L20 U/L21 U/L22 U/L23 U/L
24 U/L25 U/L26 U/L27 U/L28 U/L29 U/L30 U/L31 U/L
32 U/L33 U/L34 U/L35 U/L36 U/L37 U/L38 U/L39 U/L
40 U/L41 U/L42 U/L43 U/L44 U/L45 U/L46 U/L47 U/L
48 U/L49 U/L50 U/L51 U/L52 U/L53 U/L54 U/L55 U/L
Medically reviewed by Javier Muga Bustamante Ph.D. on 26/03/2020


  • Concise Book of Medical Laboratory Technology: Methods and Interpretations. 2nd Edition. 2015. Ramnik Sood. ISBN: 978-93-5152-333-8. Pag. 536.
  • Thomas L. Gamma glutamyltransferase (GGT). In:Thomas L, ed. Clinical laboratory diagnostics. Use and assessment of clinical laboratory results. Frankfurt/Main: TH-Books erlagsgesellschaft, 1998:80-86. 65 ISBN: 9783980521543.
  • Tietz NW, ed. Clinical guide to laboratory tests, 3rd ed. Philadelphia: WB Saunders Company,1995:286-87. ISBN 9780721656106.
  • Common Terminology Criteria for Adverse Events (CTCAE). Version 5.0.Published: November 27, 2017. U.S. Department of health and human Services. Available on:
  • Severity grading in drug induced liver injury. U.S. National Library of Medicine. Available on:

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