The aspartate aminotransferase or oxaloacetic transaminase test (AST or TGO) is a blood test requested to investigate injuries that compromise the normal functioning of the liver, such as hepatitis or cirrhosis, for example.
Oxaloacetic transaminase, or aspartate aminotransferase, is an enzyme present mainly in the liver, muscles and heart and, therefore, is normally elevated due to liver problems and conditions such as heart attack, ischemia and muscle injuries.
As a marker of liver health, AST is normally measured together with ALT, an enzyme that is also used to complement the assessment of this organ. O AST reference value is between 5 and 40 U/L of blood, which may vary according to the laboratory.
What does high AST mean?
Although the AST/ TGO exam is not very specific, the doctor can request this exam along with others that indicate liver health, such as gamma-glutamyl transferase (GGT), alkaline phosphatase (ALK) and, mainly, ALT/ TGP. .
Increased AST, or high TGO, may indicate:
- Liver problems, such as hepatitis or cirrhosis;
- Pancreatitis;
- Heart attack or heart failure;
- Muscle injury;
- Lack of oxygen or blood to the liver;
- Severe burns;
- Side effects of some medicines;
- Liver cancer.
Values above 150 U/L generally indicate liver damage and above 1000 U/L may indicate hepatitis caused by the use of medications, such as paracetamol, or ischemic hepatitis, for example. On the other hand, decreased AST values may indicate vitamin B6 deficiency in the case of people who need to undergo dialysis.
Do you have questions about your exam results?
The Ritis ratio is used in medical practice to assess the extent of liver damage and thus establish the best treatment for the situation. This ratio takes into account the AST and ALT values and when greater than 1 is indicative of more serious injuries, such as cirrhosis or liver cancer, for example. When lower than 1, it may indicate the acute phase of viral hepatitis, for example.
When the exam is requested
The TGO/AST blood test can be requested by the doctor when it is necessary to assess the health of the liver, after observing that the person is overweight, has fatty liver or presents signs or symptoms such as yellowish skin color, pain on the right side of the abdomen or in case of light stools and dark urine.
Other situations where it may also be useful to evaluate this enzyme are after the use of medications that can damage the liver and to evaluate the liver of people who consume a lot of alcoholic beverages.
Bibliography
- YONEDA, Giane S. Is it necessary to simultaneously measure ALT and AST aminotransferases?. Professional improvement work, 2016. Faculty of Medicine of Ribeirão Preto, University of São Paulo.
- TELLI, Elisa Maria R.; FRIGERI, Michele; MELLO, Sandra Regina. Assessment of liver enzyme activity in ethanol dependents, ex-dependents and non-users. RBAC. Vol 48. 3 ed; 245-252, 2016
- BARBOSA, Kátia V.; SOUZA, Aécio Flávio M.; CHEBLI, Júlio Maria F. et al. Management of laboratory abnormalities of liver enzymes in asymptomatic patients. Official medical magazine of the University Hospital of the Federal University of Juiz de Fora. Vol 31. 3 ed; 44-48, 2005
