Review of liver enzymes ALT and AST


Liver enzymes are substances produced by the liver that can be measured with a blood test. Any increase in enzyme levels can be a sign of a liver problem.

aspartate aminotransferase (AST) and alanine aminotransferase (ALT) – these are the two enzymes that doctors are paying attention to when trying to find out if you have liver problems. When used in comparison to each other, AST and ALT can help identify toxins in the liver, liver disease, or liver damage.

This article will discuss liver enzymes ALT and AST. It will tell you about what they are doing inside your body and what happens when you have elevated levels of ALT or AST.

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Roles of AST and ALT

Aminotransferases – these are the chemicals the liver uses to produce glycogen. Glycogen is a stored form glucose. It is the sugar that the body uses for energy. Any glucose that is not used right away will be converted to glycogen. It is then stored in cells for later use. Most of it will be stored in the liver. The remaining quantity will be stored in the warehouse in:

Aspartate aminotransferase (AST) it is found in several tissues, including the liver, brain, pancreatic iron, heart, kidney lungs and skeletal muscles. If any of these tissues are damaged, the AST will be expelled into the bloodstream. Although an elevated AST level is a sign of tissue damage, it is not always related to the liver.

Front, alanine aminotransferase (ALT) it is found mainly in the liver. If you have high ALT levels, it may be a sign of liver damage. It can be a minor or serious illness. An occasional increase may occur when you have a short-term infection or illness. Sustained growth is more severe. This is because it may mean the presence of an underlying disease and a greater chance of liver damage.

Normal Lab Performance

AST and ALT are measured in international units per litre (IU/l). Normal levels vary depending on body mass index (BMI) and they also depend on the person’s lab reference value or blood test results. Generally speaking, the normal reference value for adults is:

  • AST: 8 to 48 IU / l
  • ALT: 7 to 55 IU / l

The upper limit of the reference range is called the upper limit of the standard (ULN). This number is used to determine how high your liver enzymes are.

Moderate elevations are generally considered two to three times higher than the ulna. In some liver diseases, levels may be more than 50 times higher than the ulna. Levels of this high level are described as abnormal.

AST / ALT Ratio

While it may seem that a high level of ALT is all that is needed to diagnose liver disease, its association with AST can provide valuable clues as to what exactly is happening. It will also tell you if the problem is acute (occurring suddenly and progressing rapidly) or chronic (old or permanent).

If the liver experiences an acute injury, you can expect a sudden increase in ALT. On the other hand, if liver disease progresses slowly, liver damage will also gradually affect other organs. As these organs are damaged, the AST will begin to rise.

Occurs in diseases such as hepatitis C. This causes long-term liver damage that causes symptoms including:

  • Kidney
  • Brain
  • Eyeshadow
  • Skin
  • Joints (called extrahepatic symptoms)

This enzyme ratio can be described diagnostically by the AST / ALT ratio. This is a calculation that compares the levels of AST and ALT in your blood. Depending on what value is raised and how much it is raised, doctors can often have a pretty clear idea of what disease is related.

What the AST / ALT ratio shows

The AST / ALT ratio is important because the elevation pattern can tell a lot about the corresponding state. These are the general guidelines used to diagnose liver disease:

  • The AST / ALT ratio is less than a unit (where ALT is significantly higher than AST) means you can have nonalcoholic fatty liver disease.
  • A ratio AST / ALT equal to one (where ALT is equal to AST) can be a sign acute viral hepatitis or drug-related liver toxicity.
  • The AST / ALT ratio is higher than the unit (where AST is higher than ALT) means you can have liver cirrhosis livers.
  • An AST / ALT ratio greater than 2:1 (where AST is more than double ALT) is a sign of alcoholic liver disease.

However, the disease cannot be diagnosed by the nature of the elevation alone. It is also necessary to measure the amount of height described in ULN multiples. Only when a quantity exceeds a certain threshold, this relationship can be considered diagnostic.

When Testing Is Recommended

AST and AST are part of a comprehensive test panel known as liver function test (LFT). LFT can be ordered:

  • If you have symptoms of liver disease, including jaundice. dark urine, queasy. vomiting and fatigue
  • To control the progression of liver disease
  • To determine when to begin a specific drug treatment
  • To check your response to liver treatment

Even going beyond liver disease, the LFT can determine whether liver damage causes a medication (prescription or over-the-counter) or an herbal medication.

If the lab test is processed on site, the results can be returned within a few hours. Otherwise, your doctor will usually get the results within one to three days.


The liver enzymes ALT and AST are produced by the liver. You can check your levels with a blood test. If you have elevated liver enzymes, it may be a sign that you have liver disease. AST is found in the liver, brain, pancreas, heart, kidneys, lungs, and skeletal muscles. ALT is found mainly in the liver.

If your AST level is too high, it may be a sign of tissue damage, not necessarily to the liver. High ALT levels may mean you have liver damage. It can also be a sign that you have a short-term infection or illness.

Frequently asked questions

  • High levels of AST (aspartate aminotransferase) may indicate problems with your liver. However, this usually does not mean that you have a disease that needs treatment. This can be a side effect of medications. A very high level of AST may indicate hepatitis, liver cirrhosis, mononucleosis, heart problems, or pancreatitis. 

  • The upper limit of the standard for AST is 48 IU / L. Levels that double or triple the upper limit of the standard are considered to be slightly elevated. In liver disease, the AST level may exceed 50 times the upper limit of normal. The medical term for this is abnormal levels.

  • High alanine transaminase (ALT) levels may indicate liver problems, but do not necessarily mean you have health problems. A very high level of ALT may indicate liver damage as a result of hepatitis, infection, liver cancer, or liver disease. High ALT levels can also be a side effect of some medications.

  • The upper limit of the standard for ALT is 55 IU/L. When the ALT level is two or three times the upper limit of the standard, it is considered to be slightly elevated. The highly elevated ALT levels found in liver disease are often 50 times higher than the upper limit of normal.

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