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Aspartate Aminotransferase 

  • Author: Sridevi Devaraj, PhD, DABCC, FACB; Chief Editor: Thomas M Wheeler, MD  more...
 
Updated: Jan 13, 2015
 

Reference Range

The reference range for aspartate aminotransferase (AST) is as follows:

  • Males: 6-34 IU/L
  • Females: 8-40 IU/L
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Interpretation

Conditions associated with very high aspartate aminotransferase levels (more than 10 times the highest normal value) are as follows:

  • Liver damage (acute viral hepatitis, toxins/drugs including acetaminophen overdose, acute fulminant hepatitis)
  • Tumor necrosis

Conditions associated with moderately high aspartate aminotransferase levels are as follows:

  • Chronic liver disease
  • Alcohol abuse
  • Cholestasis
  • Heart damage (heart attack, heart failure)
  • Kidney damage
  • Muscle injury (muscular dystrophy, dermatomyositis, trauma)
  • Hemolysis
  • Heatstroke (level dependent on extent of tissue damage)
  • High consumption of vitamin A
  • Pulmonary embolism

Conditions associated with slightly high levels of aspartate aminotransferase are as follows:

  • Fatty change in the liver
  • Alcohol abuse
  • Cirrhosis
  • Mononucleosis
  • Drugs (ie, statins, aspirin, barbiturates, HIV medication, herbs)
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Collection and Panels

Collection and panel details are as follows:

  • Specimen: Blood serum
  • Collection: Red top tube (see image below)
    Red vacutainer tube. Red vacutainer tube.
  • Panels: Liver function panel
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Background

Description

AST is an enzyme found primarily in the liver and heart, but it is also found in many other tissues including the muscle, red blood cells, pancreas, kidney, and brain. Damage to these organs or hemolysis releases the enzyme, resulting in elevated AST levels in the serum. Serum levels generally parallel the extent of damage.[1]

Another enzyme, alanine aminotransferase or ALT, is primarily found in the liver. AST and ALT are often measured together as part of a liver function panel to detect liver damage. Liver diseases in which AST is higher than ALT include alcohol-induced liver damage, cirrhosis, and liver tumors. AST formerly was called serum glutamic oxaloacetic transaminase (SGOT). Aspartate transaminase catalyzes the interconversion of aspartate and α-ketoglutarate to glutamate.

Aspartate (Asp) + α-ketoglutarate ⇌ oxaloacetate + glutamate (Glu)

Indications/Applications

This test is indicated when liver disease is suspected (ie, jaundice, fatigue, loss of appetite, abdominal pain, nausea, vomiting, dark urine, pale colored stools, itching, ascites, mental changes, history of alcohol abuse, suspected acetaminophen overdose, family history of liver disease, exposure to hepatitis viruses).

This test is used to monitor liver function (ie, use of potentially hepatotoxic drugs, treatment of or status of chronic liver disease, hepatitis, alcohol-induced liver disease, cirrhosis, fatty liver disease, hepatic failure, Wilson’s disease, hemochromatosis).[2]

Considerations

Keep in mind the following:

  • The AST:ALT ratio (De Ritis ratio) can be used to determine alcohol-induced liver disease with AST:ALT ratio of greater than 2. [3]
  • Elevated AST and normal ALT can indicate a normal liver, but damage to other organs and/or hemolysis. In acute hepatitis, AST levels usually stay high for about 1–2 months but can take as long as 3–6 months to return to normal. In chronic hepatitis, AST levels are usually not as high, often less than 4 times the highest normal level. Such smaller increases may also be seen when the bile ducts are blocked, or with certain cancers of the liver. [4] AST is may also increased after heart attacks/muscle injury, usually more than ALT.
  • Both AST and ALT are dependent on vitamin B6 (pyridoxal phosphate). Assays for AST and ALT assume adequate levels of vitamin B6 to accurately measure AST and ALT levels. Vitamin B6 depletion can result in artificially low AST and ALT levels.
  • Pregnancy may decrease AST levels.
  • Muscle damage including muscle injections and strenuous exercise can increase AST levels.
  • Hemolyzed specimens should not be used.
  • AST is stable at 4 º C for up to 48 hours.
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Contributor Information and Disclosures
Author

Sridevi Devaraj, PhD, DABCC, FACB Medical Director of Clinical Chemistry and POCT, Texas Children's Hospital; Professor of Pathology and Immunology, Baylor College of Medicine; Associate Director of Translation, Texas Children's Microbiome Center

Disclosure: Nothing to disclose.

Coauthor(s)

Vicki H Chu, MD Resident Physician in Anatomic and Clinical Pathology, Baylor College of Medicine

Vicki H Chu, MD is a member of the following medical societies: College of American Pathologists, United States and Canadian Academy of Pathology

Disclosure: Nothing to disclose.

Chief Editor

Thomas M Wheeler, MD Chairman, Department of Pathology and Immunology, WL Moody, Jr, Professor of Pathology, Professor of Urology, Baylor College of Medicine

Thomas M Wheeler, MD is a member of the following medical societies: Alpha Omega Alpha, American Association for Cancer Research, American Medical Association, American Society for Clinical Pathology, American Society of Cytopathology, American Thyroid Association, American Urological Association, College of American Pathologists, United States and Canadian Academy of Pathology, International Society of Urological Pathology, Harris County Medical Society

Disclosure: Received stock from PathXL for medical advisory board. for: PathXL, Inc.

References
  1. Burris CA, Ashwood ER, Burns DE. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 4th ed. St. Louis: Elsevier Saunders; 2006.

  2. Wei J, Rau M, Geier A. Non-alcoholic Fatty liver disease: epidemiology, clinical course, investigation, and treatment. Dtsch Arztebl Int. 2014 Jun 27. 111(26):447-52. [Medline]. [Full Text].

  3. Opio CK, Seremba E, Ocama P, Lalitha R, Kagimu M, Lee WM. Diagnosis of alcohol misuse and alcoholic liver disease among patients in the medical emergency admission service of a large urban hospital in Sub-Saharan Africa; a cross sectional study. Pan Afr Med J. 2013. 15:23. [Medline]. [Full Text].

  4. Toro A, Ardiri A, Mannino M, Arcerito MC, Mannino G, Palermo F, et al. Effect of pre- and post-treatment a-fetoprotein levels and tumor size on survival of patients with hepatocellular carcinoma treated by resection, transarterial chemoembolization or radiofrequency ablation: a retrospective study. BMC Surg. 2014 Jul 4. 14(1):40. [Medline]. [Full Text].

 
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Red vacutainer tube.
 
 
 
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