Elevated transaminases

Elevated transaminases can be an indicator of liver damage. Your liver, has a variety of transaminases to synthesize and break down amino acids and to interconvert energy storage molecules. The concentrations of these in the serum (the non-cellular portion of blood) are normally low. However, if the liver is damaged, the hepatocyte cell membrane becomes more permeable and some of the enzymes leak out into the blood stream. The two transaminases commonly measured are alanine transaminase (ALT) and aspartate transaminase (AST). These levels previously were called the serum glutamate-pyruvate transaminase (SGPT) and the serum glutamate-oxaloacetate transaminase (SGOT). Elevated liver transaminases levels are quite sensitive for liver injury, meaning that they are likely to be present if there is injury. However, they may also be elevated in other conditions. Alanine aminotransferase (ALT) is an enzyme found mostly in the cells of your liver and kidney. Much smaller amounts of it are also found in your heart and muscles. Normally, ALT levels in blood are low, but when your liver is damaged, ALT is released into the blood and the level increases. On the other hand, aspartate aminotransferase (AST) is an enzyme found in cells throughout your body but mostly in your heart and liver and, to a lesser extent, in your kidneys and muscles. In healthy individuals, levels of aspartate aminotransferase (AST) in the blood are low. When liver or muscle cells are injured, they release aspartate aminotransferase (AST) into the blood. The alanine aminotransferase (ALT) test is typically used to detect liver injury. It is often ordered in conjunction with aspartate aminotransferase (AST) as part of a liver panel or comprehensive metabolic panel (CMP) to screen for and/or help diagnose liver disease. A number of conditions can cause injury to liver cells and may cause increases in aspartate transaminase (AST). The aspartate transaminase (AST) test is most useful in detecting liver damage due to hepatitis, drugs toxic to the liver, cirrhosis, or alcoholism. Aspartate aminotransferase (AST), however, is not specific for the liver and may be increased in conditions affecting other parts of the body.

A low levels of alanine transaminase (ALT) and aspartate transaminase (AST) in the blood are expected and are normal.

The liver is a vital organ located in the upper right-hand side of the abdominal area just beneath the rib cage. It is involved in many important functions in the body. The liver helps to process the body’s nutrients, manufactures bile to help digest fats, produces many important proteins such as blood clotting factors, and breaks down potentially toxic substances into harmless ones that the body can use or excrete.

In general, any damage to the liver will cause medium elevations in these transaminases (usually called liver enzymes, though of course they are not the only enzymes in the liver). And diagnosis requires synthesis of many pieces of information, including the patient’s history, physical examination, and possibly imaging or other laboratory examinations. However, very high elevations of the transaminases suggests severe liver damage, such as viral hepatitis, liver injury from lack of blood flow, or injury from drugs or toxins. Most disease processes cause alanine transaminase (ALT) to rise higher than aspartate transaminase (AST).

The function of alanine transaminase (ALT) is to convert alanine, an amino acid found in proteins, into pyruvate, an important intermediate in cellular energy production. In healthy individuals, ALT levels in the blood are low. When the liver is damaged, alanine aminotransferase (ALT) is released into the blood, usually before more obvious signs of liver damage occur, such as jaundice.

A number of conditions can cause damage to liver cells, resulting in an increase in alanine transaminase (ALT). The alanine transaminase (ALT) test is most useful in detecting damage due to hepatitis (inflammation of the liver) or as a result of drugs or other substances that are toxic to the liver.

Alanine transaminase (ALT) is commonly tested in conjunction with aspartate aminotransferase (AST), another liver enzyme, as part of a liver panel. Both alanine transaminase (ALT) and aspartate transaminase (AST) levels usually rise whenever the liver is being damaged, although alanine transaminase (ALT) is more specific for the liver and, in some cases, may be the only one of the two to be increased. An AST/ALT ratio may be calculated to aid in distinguishing between different causes and severity of liver injury and to help distinguish liver injury from damage to heart or muscles.

Alanine transaminase (ALT) values are often compared to the results of other tests such as alkaline phosphatase (ALP), gamma glutamyl transferase (GGT), total protein, albumin-to-globulin ratio (A/G ratio), and bilirubin to help determine which form of liver disease is present.

Alanine transaminase (ALT) is often used to monitor the treatment of liver disease, to see if the treatment is working, and may be ordered either by itself or along with other tests for this purpose.

When is liver transaminases test ordered?

The blood test for aspartate aminotransferase (AST) and alanine aminotransferase (ALT) may be ordered as part of a comprehensive metabolic panel (CMP) when you have a routine health examination.

A healthcare practitioner usually orders an alanine transaminase (ALT) and aspartate transaminase (AST) test and several others when you have signs and symptoms of a liver disorder. Some of these signs and symptoms may include:

• Weakness, fatigue
• Loss of appetite
• Nausea, vomiting
• Abdominal distension/fullness and/or pain
• Jaundice (icterus)
• Dark urine or tea-colored urine
• Light-colored stool or clay-colored stool
• Skin itchiness (pruritus)
• Weakness, fatigue
• Swelling in the legs and ankles
• Tendency to bruise easily

Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) are considered to be two of the most important tests to detect liver injury, although alanine transaminase (ALT) is more specific for the liver than is aspartate aminotransferase (AST) and is more commonly increased than is AST. Sometimes aspartate aminotransferase (AST) is compared directly to alanine transaminase (ALT) and an AST/ALT ratio is calculated. This ratio may be used to distinguish between different causes of liver damage and to distinguish liver injury from damage to heart or muscle.

Alanine transaminase (ALT) may also be ordered, either by itself or with other tests, when you have an increased risk for liver disease. This is because many people with mild liver damage will have no signs or symptoms. Even without symptoms, alanine transaminase (ALT) can be increased with mild liver damage. You may be at risk of liver disease when you:

• Have a history of known or possible exposure to hepatitis viruses
• Are a heavy alcohol drinker
• Have a family history of liver disease
• Take drugs that might damage the liver, such as acetaminophen
• Are overweight, obese and/or have diabetes or metabolic syndrome

Alanine transaminase (ALT) may also be ordered on a regular basis when it is used to monitor the treatment of liver disease.

Aspartate aminotransferase (AST) levels are often compared with results of other tests such as alkaline phosphatase (ALP), total protein, and bilirubin to help determine which form of liver disease is present.

Aspartate aminotransferase (AST) is often measured to monitor treatment of persons with liver disease and may be ordered either by itself or along with other tests for this purpose.

Sometimes aspartate aminotransferase (AST) may be used to monitor people who are taking medications that are potentially toxic to the liver. If aspartate aminotransferase (AST) levels increase, then the person may be switched to another medication.

What other tests may be used to help determine the cause of liver damage?

After a thorough physical exam and evaluation of a person’s medical history, there are several other tests that may be performed as follow up depending on what is suspected to be the cause of liver damage. Some of these include:

• Tests for hepatitis A, hepatitis B, and hepatitis C
• Testing for exposure to drugs and other substances toxic to the liver (hepatotoxicity).
• Ethanol level
• Copper and ceruloplasmin for Wilson disease
• Iron tests and genetic tests for hereditary hemochromatosis

A liver biopsy may be performed to help determine the cause of liver injury and to evaluate the extent of liver damage.

Elevated transaminase level

Elevated levels of alanine transaminase (ALT)

Liver disease is the most common reason for higher than normal levels of alanine transaminase (ALT).

Very high levels of alanine transaminase (ALT) (more than 10 times normal) are usually due to acute hepatitis, sometimes due to a viral hepatitis infection. In acute hepatitis, alanine transaminase (ALT) levels usually stay high for about 1-2 months but can take as long as 3-6 months to return to normal. Levels of alanine transaminase (ALT) may also be markedly elevated (sometimes over 100 times normal) as a result of exposure to drugs or other substances that are toxic to the liver or in conditions that cause decreased blood flow to the liver.

Alanine transaminase (ALT) levels are usually not much elevated in chronic hepatitis, often less than 4 times normal. In this case, alanine transaminase (ALT) levels often vary between normal and slightly increased, so the test may be ordered frequently to see if there is a pattern. Other causes of moderate increases in alanine transaminase (ALT) include obstruction of bile ducts, cirrhosis (usually the result of chronic hepatitis or bile duct obstruction), heart damage, alcohol abuse, and with tumors in the liver.

Alanine transaminase (ALT) is often performed together with a test for aspartate transaminase (AST) or as part of a liver panel. For more about alanine transaminase (ALT) results in relation to other liver tests, see the Liver Panel article.

In certain types of liver diseases, the alanine transaminase (ALT) level is higher than aspartate transaminase (AST) and the AST/ALT ratio will be low (less than 1). There are a few exceptions; the AST/ALT ratio is usually greater than 1 in alcoholic hepatitis, cirrhosis, and with heart or muscle injury and may be greater than 1 for a day or two after onset of acute hepatitis.

What conditions other than liver problems can cause elevated alanine transaminase (ALT)?

Alanine transaminase (ALT) is more specific for the liver than aspartate transaminase (AST) and so is much less affected by conditions affecting other parts of the body. Nevertheless, injury to organs other than the liver, such as the heart and skeletal muscle, can cause elevations of alanine transaminase (ALT). For example, small increases may be seen with skeletal muscle damage or heart attacks.

A shot or injection of medicine into the muscle tissue, or strenuous exercise, may increase alanine transaminase (ALT) levels.

Many drugs may raise alanine transaminase (ALT) levels by causing liver damage in a very small percentage of patients taking the drug. This is true of both prescription drugs and some “natural” health products. Be sure to tell your healthcare provider about all of the drugs and/or health supplements you are taking.

Elevated levels of aspartate transaminase (AST)

Very high levels of aspartate transaminase (AST) (more than 10 times normal) are usually due to acute hepatitis, sometimes due to a viral infection. With acute hepatitis, aspartate transaminase (AST) levels usually stay high for about 1-2 months but can take as long as 3-6 months to return to normal. Levels of aspartate transaminase (AST) may also be markedly elevated (often over 100 times normal) as a result of exposure to drugs or other substances that are toxic to the liver as well as in conditions that cause decreased blood flow (ischemia) to the liver.

With chronic hepatitis, aspartate transaminase (AST) levels are usually not as high, often less than 4 times normal, and are more likely to be normal than are alanine transaminase (ALT) levels. aspartate transaminase (AST) often varies between normal and slightly increased with chronic hepatitis, so the test may be ordered frequently to determine the pattern. Such moderate increases may also be seen in other diseases of the liver, especially when the bile ducts are blocked, or with cirrhosis or certain cancers of the liver. aspartate transaminase (AST) may also increase after heart attacks and with muscle injury, usually to a much greater degree than alanine transaminase (ALT).

Aspartate transaminase (AST) is often performed together with the alanine transaminase (ALT) test or as part of a liver panel. For more about aspartate transaminase (AST) results in relation to other liver tests, see the Liver Panel article.

In most types of liver disease, the alanine transaminase (ALT) level is higher than aspartate transaminase (AST) and the AST/ALT ratio will be low (less than 1). There are a few exceptions; the AST/ALT ratio is usually increased in alcoholic hepatitis, cirrhosis, hepatitis C virus-related chronic liver disease, and in the first day or two of acute hepatitis or injury from bile duct obstruction. With heart or muscle injury, aspartate transaminase (AST) is often much higher than alanine transaminase (ALT) (often 3-5 times as high) and levels tend to stay higher than alanine transaminase (ALT) for longer than with liver injury.

What conditions other than liver problems can cause elevated aspartate transaminase (AST)?

Conditions that affect other organs, such as the heart and skeletal muscle, can cause elevations of aspartate transaminase (AST). Mild to moderate increases may be seen with vigorous exercise and skeletal muscle injury or in conditions such as acute pancreatitis and heart attacks.

Pregnancy, a shot or injection of medicine into muscle tissue, or even strenuous exercise may increase aspartate transaminase (AST) levels. Acute burns, surgery, and seizures may raise aspartate transaminase (AST) levels as well.

In rare instances, some drugs can damage the liver or muscle, increasing aspartate transaminase (AST) levels. This is true of both prescription drugs and some “natural” health products. Be sure to tell your healthcare practitioner about all of the drugs and/or health supplements that you are taking.