The liver is one of the most important organs in the body, as it helps detoxify the blood of noxious chemicals and substances. It also serves as a reservoir for glucose, the main sugar used for the body's various energy needs. Inside the liver cells are enzymes that help it perform its various functions. Elevated liver enzymes in the bloodstream can result from damage to liver cells.
Types
Two main liver enzymes are measured in blood tests: alanine transaminase, or ALT, and aspartate transaminase, or AST. According to Lab Tests Online, the level of ALT is a more specific test of liver damage than AST because AST is also found in other organs, such as the kidneys, heart and muscles. These two are often part of a test panel called the liver, or hepatic panel, which tests the level of several substances and enzymes to detect evidence of liver damage, infection or inflammation.
Function
Liver enzymes have several functions within the liver cells. Both transaminases are important in the processing of certain proteins in the liver. They also help with the liver's release of glucose into the bloodstream. But their main clinical significance is in their detection of liver damage.
Causes
According to the Mayo Clinic, the most common causes of elevated liver enzymes include infection, inflammation, trauma and chemically induced damage to liver cells. Hepatitis, an infection of the liver caused by various viruses, can cause elevated liver enzymes. In adults, alcoholism is a common cause of liver damage and inflammation. Over-the-counter and prescription medicines can overwhelm the liver's ability to detoxify the blood, resulting in elevated liver enzymes. Other causes of elevated liver enzymes include obesity, cancer and autoimmune hepatitis.
Features
Usually, a physician will order tests looking for elevated liver enzymes if the patient has symptoms of liver disease. According to Lab Tests Online, these include weakness, fatigue, loss of appetite, nausea, vomiting, abdominal swelling, pain -- especially in the right upper area of the abdomen, where the liver is located -- and jaundice, a yellowish discoloration of the skin resulting from the accumulation of bilirubin, another compound processed by the liver.
Considerations
Very high levels of ALT are usually due to viral hepatitis. The elevation can last for months before levels return to normal. Even though ALT is usually more elevated than AST in cases of liver damage, there are circumstances when the opposite is true. For example, AST can be more elevated in cases of alcoholic liver cirrhosis or hepatitis.
