SGOT and AST are two names for the same thing: an enzyme found mainly in your liver, heart, and muscles that shows up on routine blood work. SGOT stands for serum glutamic-oxaloacetic transaminase, the older name you might see on lab reports. AST, or aspartate aminotransferase, is the modern term. When cells in these organs are damaged or inflamed, they release AST into your bloodstream, which is why elevated levels can signal a problem worth investigating.
What AST Actually Does in Your Body
AST is an enzyme, meaning it speeds up a specific chemical reaction. Its job is shuttling amino groups between two amino acids, aspartate and glutamate, a process that helps your body break down proteins and produce energy. This reaction happens constantly in healthy tissue.
The enzyme exists in two forms inside your cells. One floats in the main body of the cell (the cytoplasm), while the other is tucked inside the mitochondria, the cell’s energy-producing structures. This matters because the mitochondrial form only escapes into the blood when cell damage is more severe, not just surface-level irritation. Your liver contains the highest concentration of AST, but significant amounts also sit in your heart muscle, skeletal muscles, red blood cells, and kidneys.
Normal AST Ranges
AST is measured in units per liter (U/L). Normal ranges vary slightly between labs, but the Mayo Clinic lists general reference values as 8 to 48 U/L for males and 8 to 43 U/L for females (ages 14 and older). Some labs use tighter ranges. The University of Rochester, for example, lists 14 to 20 U/L for men and 10 to 36 U/L for women. Your lab report will print its own reference range next to your result, so use that as your benchmark rather than memorizing a single number.
Age, sex, and body mass all influence where your baseline falls. A result slightly outside the reference range on a single test isn’t automatically a diagnosis of anything. Doctors typically look at trends over time and at other markers tested alongside AST.
Why Your Doctor Orders This Test
AST is part of the comprehensive metabolic panel (CMP) and the liver function panel, two of the most commonly ordered blood tests. Your doctor may request it during a routine physical, to monitor a known liver condition, or to check whether a medication you’re taking is affecting your liver. It’s also ordered when symptoms like fatigue, nausea, abdominal pain, or yellowing of the skin suggest possible liver involvement.
AST is rarely interpreted alone. It’s almost always read alongside ALT (alanine aminotransferase), another liver enzyme. ALT is more specific to the liver than AST, so comparing the two helps narrow down whether the liver is the actual source of the problem or whether something else, like muscle damage, is driving the numbers up.
What Causes High AST Levels
Liver-Related Causes
The most common reason for elevated AST is some form of liver stress or injury. This includes nonalcoholic fatty liver disease (the single most common cause in Western countries), hepatitis B and C, excessive alcohol use, cirrhosis, and reactions to certain medications. In most of these conditions, ALT rises alongside AST. When the cause is direct damage to liver cells, ALT typically rises more than AST because ALT has a longer half-life in the blood and a greater share of AST is trapped inside mitochondria rather than floating freely in the cell.
Non-Liver Causes
Because AST lives in multiple organs, an elevated result doesn’t automatically point to the liver. Heart attacks release AST from damaged cardiac muscle. Skeletal muscle injuries, including intense exercise, can push AST well above normal. Muscle disorders like polymyositis, an underactive thyroid, and even the destruction of red blood cells (hemolysis) during the blood draw itself can all inflate the number.
Exercise is an underappreciated cause. A case study published in the Journal of Family Medicine and Primary Care documented clearly abnormal liver panels in a healthy adult male whose only explanation was exercise-induced muscle damage and changes in liver cell membrane permeability from intense workouts. The authors noted that intense exercise is an extrahepatic cause of elevated liver function tests that clinicians should consider before ordering further workups.
The AST/ALT Ratio and What It Reveals
Dividing your AST value by your ALT value produces what’s called the De Ritis ratio, first described in 1957 and still used today. This single number helps distinguish between different types of liver disease.
In most forms of liver inflammation, including viral hepatitis, ALT runs higher than AST, giving a ratio below 1. In alcohol-related liver disease, the pattern flips: AST is typically higher than ALT, producing a ratio of 2:1 or greater. Studies have found an average ratio as high as 2.3:1 in patients with alcoholic liver disease, compared to about 1.1:1 in healthy controls. A ratio above 2, especially when combined with elevations in another enzyme called GGT (gamma-glutamyl transferase), strongly suggests alcohol as the culprit.
The ratio isn’t a standalone diagnostic tool, but it gives your doctor a useful signal about where to look next.
Things That Can Skew Your Results
Several everyday factors can temporarily raise AST without any underlying disease. Heavy exercise in the 24 to 72 hours before your blood draw is one of the most common. Alcohol consumption, even moderate amounts, can bump the number. Certain supplements, including some herbal products marketed for liver health, can paradoxically stress the liver and raise AST. Performance-enhancing drugs like anabolic steroids are a well-documented cause.
If your AST comes back elevated and your doctor suspects a benign cause, they’ll often ask you to avoid intense exercise and alcohol for a few days, then retest. A result that normalizes on the second draw is reassuring. One that stays elevated or climbs warrants further investigation, which might include imaging of the liver or testing for specific infections.
What Low AST Levels Mean
Low AST values rarely get attention because they don’t carry the same clinical weight as high values. A low reading generally means your liver, heart, and muscle cells are intact and not releasing extra enzyme into the bloodstream. In some cases, very low AST has been loosely associated with vitamin B6 deficiency, since B6 is a cofactor the enzyme needs to function. But a low AST on its own is not something most doctors act on or worry about.
How AST Fits Into the Bigger Picture
A single AST number is a starting point, not a conclusion. Doctors interpret it alongside ALT, alkaline phosphatase, bilirubin, albumin, and other markers that together paint a picture of how well your liver is functioning. If all of those values are normal and only AST is mildly elevated, the source is often muscular rather than hepatic. If multiple liver markers are abnormal, the workup shifts toward identifying the specific liver condition involved.
The test itself is a simple blood draw with no special preparation required in most cases, though some providers may ask you to fast if AST is being run as part of a broader metabolic panel. Results typically come back within a day or two.