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The Significance of Elevated Liver Enzymes

Elevated liver enzymes usually indicate an injury or inflammation of the liver. However, the range of causes of an abnormally high level of liver enzymes is extremely wide, and such a result from a liver function test is not necessarily indicative of serious illness. Your doctor will want to know what medications you've been taking and may need to order further tests to pinpoint the reason for the elevated reading.

  1. Liver Function Test

    • A liver function test is actually a series of blood tests designed to measure the levels of various substances in the blood. Together, these tests provide doctors with a helpful overview of how well your liver is working. According to the Simple Facts Project website, these tests measure the levels of four key liver enzymes, as well as total protein, cholesterol, bilirubin and albumin. The enzymes measured include aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT) and alkaline phosphatase (ALP).

    Function of Liver Enzymes

    • AST and ALT are enzymes produced in the liver to assist in the production of proteins and the metabolism of amino acids. When the liver is damaged or inflamed, these enzymes leak into the bloodstream. GGT and ALP are known as cholestatic enzymes, and elevated levels of these enzymes usually indicate a problem with the bile ducts that transport bile from the liver to the gall bladder and the intestines. The term "cholestasis" is used to describe a partial or full blockage of the bile ducts, according to the Simple Facts Project website.

    Elevated AST & ALT

    • Elevated levels of AST and ALT can signal a variety of conditions, ranging from inflammation caused by certain drugs and herbs to cirrhosis or liver cancer. Other causes, according to MayoClinic.com, include obesity; nonalcoholic fatty liver disease; hepatitis; chronic alcohol abuse; reactions to over-the counter (OTC) pain medications, such as acetaminophen; celiac disease; cytomegalovirus infection; dermatomyositis; Wilson's disease; hemochromatosis; and mononucleosis. According to LiverDisease.com, normal readings for AST range from 0 to 40 IU/L (international units per liter), while normal ALT levels run from 0 to 45 IU/L.

    Elevated GGT & ALP

    • High levels of GGT and ALP may be signs of diverse conditions, such as bile duct blockage, gallstones, alcoholic liver disease, nonalcoholic fatty liver disease, primary sclerosing cholangitis, liver tumors, drug-induced liver disease and primary biliary cirrhosis. Normal levels of GGT range from 3 to 60 IU/L, while normal ALP readings usually fall somewhere between 35 and 115 IU/L, according to LiverDisease.com.

    Further Testing

    • Based on what your doctor already knows of your underlying health conditions and what you tell him about your alcohol consumption and the drugs you are taking, he will order specific tests to determine why your liver enzymes are elevated.

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