Liver Blood Tests (cont.)
Charles Patrick Davis, MD, PhD
Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.
William C. Shiel Jr., MD, FACP, FACR
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
In this Article
- What are the basic functions of the liver?
- What are common liver blood tests?
- What are the aminotransferases?
- Normally, where are the aminotransferases?
- What are normal levels of AST and ALT?
- What do high (elevated) liver tests (AST and ALT) mean?
- Do AST and ALT test results indicate liver function?
- What blood tests are done to detect liver function?
- What are some common reasons for abnormal liver tests?
- What medications can cause increased liver enzyme tests (abnormal aminotransferase levels)?
- What conditions can cause very high aminotransferase levels?
- What are some of the less common causes of elevated liver blood tests?
- How are healthy people evaluated for mild to moderate rises in aminotransferase levels?
- How about monitoring liver blood tests?
- What about the other liver enzymes?
- Hepatitis Slideshow Pictures
- Take the Alcohol Quiz
- Alcohol Abuse Slideshow Pictures
What are normal levels of AST and ALT?
- The normal range of values for AST (SGOT) is about 5 to 40 units per liter of serum (the liquid part of the blood).
- The normal range of values for ALT (SGPT) is about 7 to 56 units per liter of serum.
However, the ranges of AST and ALT numbers may differ slightly depending on the technique and protocols used by different laboratories worldwide. However, normal reference ranges are routinely provided by each laboratory and printed each patient's individual report.
What do high (elevated) liver tests (AST and ALT) mean?
AST (SGOT) and ALT (SGPT) are reasonably sensitive indicators of liver damage or injury from different types of diseases or conditions. However, it must be emphasized that higher-than-normal levels of these liver enzymes should not be automatically equated with liver disease. They may mean liver problems or they may not. For example, elevations of these enzymes can occur with muscle damage. The interpretation of elevated AST and ALT results depends upon the entire clinical evaluation of an individual, and so it is best done by physicians experienced in evaluating liver disease and muscle disease.
Moreover, the precise levels of these liver enzyme tests do not correlate well with the extent of liver problems or the prognosis (outlook). Thus, the exact levels of AST (SGOT) and ALT (SGPT) cannot be used to determine the degree of liver disease or predict the future prognosis for liver function. For example, individuals with acute viral hepatitis A may develop very high AST and ALT levels (sometimes in the thousands of units/liter range), but most people with acute viral hepatitis A recover fully without residual liver disease. Conversely, people with chronic hepatitis C infection typically have only a little elevation in their AST and ALT levels while having substantial liver injury and even advanced scarring of the liver (cirrhosis) from ongoing minor inflammation of the liver.
Do AST and ALT test results indicate liver function?
It is important to clarify that ALT and AST levels do not reflect the function of the liver, even though in the medical community and in medical publications they commonly, and incorrectly, are referred to as liver function tests, or AST or ALT tests and are only used to detect inflammation due to injury or damage to the liver from any source. Even in conditions when AST and ALT are very elevated, the liver still may function properly.
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