1. Hepatitis Slideshow Pictures
2. Take the Alcohol Quiz
3. Alcohol Abuse Slideshow Pictures

Medical Author:

Siamak T. Nabili, MD, MPH

Siamak T. Nabili, MD, MPH

Dr. Nabili received his undergraduate degree from the University of California, San Diego (UCSD), majoring in chemistry and biochemistry. He then completed his graduate degree at the University of California, Los Angeles (UCLA). His graduate training included a specialized fellowship in public health where his research focused on environmental health and health-care delivery and management.

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Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

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.

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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 elevated liver tests (AST and ALT) mean?
• Does AST and ALT measurements indicate liver function?
• Which blood tests are done to detect liver function?
• What are some common reasons for abnormal liver tests?
• What medications can cause 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
• Patient Comments: Liver Blood Tests - Diagnosis
• Patient Comments: Liver Blood Tests - Why
• Patient Comments: Liver Blood Tests - Test
• Liver Blood Tests Index

What are normal levels of AST and ALT?

• The normal range of values for AST (SGOT) is from 5 to 40 units per liter of serum (the liquid part of the blood).
  
  
• The normal range of values for ALT (SGPT) is from 7 to 56 units per liter of serum.

The ranges of AST and ALT numbers may differ slightly depending on the technique and protocols used by different laboratories. However, normal reference ranges are routinely provided by each laboratory and printed in the report.

What do elevated liver tests (AST and ALT) mean?

AST (SGOT) and ALT (SGPT) are sensitive indicators of liver damage or injury from different types of diseases. But 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 levels 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 enzymes do not correlate well with the extent of liver damage 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. 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).