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Normal (ALT) Alanine Aminotransferase level in the blood

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Normal (ALT) Alanine Aminotransferase level in the blood

What is the normal level of ALT in the blood?

Adult men: 7 to 50 U/L
Adult women: 7 to 35 U/L
Children: 13 to 45 U/L

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

Adult men: 0.12 to 0.85 ukat/L
Adult women: 0.12 to 0.60 ukat/L
Children: 0.22 to 0.75 ukat/L

Why normal levels can differ across different labs?

Each laboratory must establish its own normal ranges for ALT (alanine aminotransferase) 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 ALT Alanine Aminotransferase?

The ALT (Alanine Aminotransferase), formerly named glutamic pyruvic transaminase (GPT), is an enzyme of the transaminase group synthesized in the liver cells. The ALT plays an important role in gluconeogenesis because the ALT is converted into pyruvate for glucose production.

The ALT is found predominantly in the liver, with small quantities found in the kidneys, heart and muscles.

When there is a damage to these organs, especially to the liver, the ALT secreted into the blood increases.

What is the ALT blood test used for?

The ALT (Alanine Aminotransferase) blood test is a commonly ordered blood assay used as a marker of liver inflammation or liver injury.

The ALT transaminase and the AST transaminase usually increase simultaneously when there is a liver disease. However, the ALT is more specific for liver damage. AST level will be higher than ALT in alcoholic liver disease (the AST value will be more than twice the ALT value). In viral hepatitis ALT level will be higher than AST level.

The ALT is also useful in blood donation. An elevated ALT level in blood donors has been associated with an increased risk of hepatitis transmission. For this reason, the ALT has been used in several countries to prevent transmission of hepatitis in blood donation.

Low ALT concentration can be a sign of vitamin deficiency, for example B6 vitamin deficiency. It can also be a consequence of an urinary tract infection.

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

You can visit our pages about:

Which values are considered a normal ALT 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.

ALT Alanine Aminotransferase
Status
Normality
7 U/L8 U/L9 U/L10 U/L11 U/L12 U/L13 U/L14 U/L
15 U/L16 U/L17 U/L18 U/L19 U/L20 U/L21 U/L22 U/L
23 U/L24 U/L25 U/L26 U/L27 U/L28 U/L29 U/L30 U/L
31 U/L32 U/L33 U/L34 U/L35 U/L36 U/L37 U/L38 U/L
39 U/L40 U/L41 U/L42 U/L43 U/L44 U/L45 U/L46 U/L
47 U/L48 U/L49 U/L50 U/L    
foto de Dr. Javier Muga Bustamante
Written by

Dr. Javier Muga Bustamante

Last update: 26/03/2020

Bibliography

  • Concise Book of Medical Laboratory Technology: Methods and Interpretations. 2nd Edition. 2015. Ramnik Sood. ISBN: 978-93-5152-333-8. Pag. 533.
  • Thomas L. Alanine aminotransferase (ALT), Aspartate aminotransferase (AST). In:Thomas L, ed. Clinical laboratory diagnostics. Use and assessment of clinical laboratory results. Frankfurt/Main: TH-Books Verlagsgesellschaft, 1998:55-65 ISBN: 9783980521543.
  • Schumann G, Bonora R, Ceriotti F et al. IFCC Primary Reference Procedures for the Measurement of Catalytic Activity Concentrations of Enzymes at 37°C. Part 4. Reference Procedure for the Measurement of Catalytic Concentration of Alanine Aminotransferase. Clin Chem Lab Med 2002;40:718-24.
  • Thomas L, Müller M, Schumann G et al. Consensus of DGKL and VDGH for interim reference intervals on enzymes in serum. J Lab Med 2005;29:301-08.
  • Painter PC, Cope JY, Smith JL. Chapter 50. Reference information for the clinical laboratory. In: Burtis CA, Ashwood ER, eds. Tietz textbook of clinical chemistry. Philadelphia:WB Saunders Company, 1999;1802pp. ISBN 9780721656106.
  • Common Terminology Criteria for Adverse Events (CTCAE). Version 5.0.Published: November 27, 2017. U.S. Department of health and human Services. Disponible en: https://ctep.cancer.gov
  • Severity grading in drug induced liver injury. U.S. National Library of Medicine. Disponible en: https://livertox.nih.gov

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