The acronym SGOT, or Serum Glutamic Oxaloacetic Transaminase, refers to an enzyme measured in a standard blood test. Although SGOT is still commonly used, the current medical term is AST, or Aspartate Aminotransferase. This measurement is included in a comprehensive metabolic panel or a liver function test, primarily to assess liver health. However, SGOT/AST is not exclusive to the liver, meaning an elevated result can signal potential damage in other organs as well.
What the SGOT Enzyme Is
SGOT/AST is an enzyme that plays a part in the body’s metabolism of amino acids, which are the building blocks of proteins. It facilitates the transfer of chemical groups between molecules, a process cells use to generate energy and process nutrients.
The enzyme is found in high concentrations within cells of several organs, not just the liver. While the liver contains a significant amount, SGOT/AST is also present in the heart, skeletal muscles, kidneys, and brain. Under normal conditions, only small amounts of this enzyme circulate in the bloodstream.
When cells in these organs are injured or damaged, their membranes break down, causing the SGOT/AST enzyme to leak into the general circulation. The level detected in the blood serum acts as an indirect marker, indicating the extent of tissue damage somewhere in the body. Measuring this concentration helps clinicians pinpoint where that damage may have occurred.
Normal Reference Ranges and Low Results
SGOT/AST levels are measured in units per liter (U/L) of serum. The normal range for adults typically falls between 8 and 45 U/L, though exact ranges vary slightly based on the laboratory. Some labs specify different upper limits for males (up to 40 U/L) and females (up to 32 U/L).
A result within this established range suggests that the organs where the enzyme is concentrated are healthy and not experiencing significant cell damage. Low SGOT/AST levels, meaning below the reference range, are rare and usually not a major clinical concern. They can occasionally be linked to severe malnutrition or a deficiency in Vitamin B6, which is necessary for the enzyme’s activity.
Causes of Elevated SGOT Levels
Elevated SGOT/AST levels indicate that cells containing the enzyme have been damaged, releasing their contents into the bloodstream. The degree of elevation provides an initial clue: mild increases (less than five times the upper limit) often suggest chronic conditions, while severe increases (more than ten times the upper limit) point toward acute injury. Since SGOT/AST is found in multiple tissues, a high result requires careful assessment to determine the source of the injury.
The most common primary source of elevated SGOT is damage to the liver, which occurs in a variety of hepatic diseases. Acute hepatitis, caused by viral infections or drug injury, leads to substantial enzyme leakage due to widespread liver cell death. Chronic liver conditions, such as cirrhosis, nonalcoholic fatty liver disease (NAFLD), and nonalcoholic steatohepatitis (NASH), also cause sustained SGOT elevations.
Fatty liver disease, linked to metabolic syndrome, obesity, and diabetes, is a frequent cause of mild to moderate SGOT elevation. Alcohol consumption is another major contributor, often leading to alcoholic hepatitis and liver scarring. Obstruction of the bile ducts can also cause pressure and damage to liver cells, resulting in enzyme release.
SGOT elevation is not exclusively a sign of liver damage. Significant non-liver causes include acute myocardial infarction (heart attack), where damage to the heart muscle releases large amounts of the enzyme. Severe trauma or disease affecting the skeletal muscles, such as rhabdomyolysis or muscular dystrophy, will also cause a rapid rise. Even intense physical activity or recent muscle injections can temporarily raise the enzyme concentration.
How SGOT Relates to Other Liver Tests
SGOT/AST is almost always measured as part of a liver function panel that includes ALT (Alanine Aminotransferase). ALT is a more specific indicator of liver cell injury because it is found in much higher concentrations in the liver than in other organs. Comparing the levels of both enzymes provides better diagnostic insight into the cause of the underlying damage.
The ratio of AST to ALT, known as the De Ritis ratio, is a valuable tool for differentiating liver diseases. In many non-alcoholic conditions, such as fatty liver disease and chronic viral hepatitis, the ALT level is typically higher than the AST level, resulting in a ratio less than 1.0. This pattern suggests common hepatic inflammation.
The relationship reverses in certain conditions, providing a distinct diagnostic clue. An AST/ALT ratio greater than 2.0 is highly suggestive of alcoholic liver disease, as alcohol consumption disproportionately elevates AST. A ratio greater than 1.0 in non-alcoholic liver disease can suggest advanced liver scarring, or cirrhosis. This ratio helps identify the characteristic pattern of tissue injury.