Liver Function Tests

Liver battery or liver profile.

To assess liver function and diagnose diseases of the liver and bile system.

Abnormal levels of various substances in the blood may indicate that the liver or other organs are not functioning properly. The most commonly measured substances include alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), bilirubin, and gamma glutamyl transferase (GGT).

Usually, you will be requested to refrain from consuming food and drink for at least eight hours prior to the test.

Blood is drawn from a vein in your arm and analyzed for the levels of various substances.

You follow the standard procedure after a venipuncture, and you are free to leave.

• ALP levels may be increased or decreased by certain drugs. They may also be increased in healthy people in the following situations: pregnancy, during period of rapid bone growth in puberty, chronic alcoholism, while healing from a bone fracture, after excessive consumption of vitamin D, and from consuming food, especially fatty foods, too soon before the test.
• ALT levels may be increased as a result of muscle trauma, obesity, and certain drugs.
• AST levels may be increased by regular drinking, trauma, surgery, and certain common drugs.
• Bilirubin levels may be increased by a large number of drugs, including certain antibiotics and birth control pills, and may be abnormally high as part of an adverse reaction to a blood transfusion.
• GGT levels are increased by alcohol, certain medications (particularly antiepileptic drugs), infectious mononucleosis, and eating large amounts of simple carbohydrates. They are also increased in infancy.

The tests may be ordered separately, but they often provide useful information when used in combination. For example, in acute viral hepatitis with jaundice, ALT and AST levels are increased as well as bilirubin levels, while in Gilbert's syndrome, a liver disorder that produces similar symptoms, only bilirubin is high. Individual tests may also signal the possibilities described below.

• Increased levels of ALP (an enzyme that is produced in several body organs, including the liver and bones) may signal various abnormalities, particularly diseases of the liver or bones, including obstruction of bile ducts, cirrhosis of the liver, hepatitis, cancer metastases to the liver or bone, diabetes, Paget's disease, osteomalacia, and rickets.
• Decreased ALP levels may signal an underactive thyroid gland, malnutrition, vitamin D deficiency, or pernicious anemia, requiring further tests. However, ALP levels may be altered by many harmless factors that must be taken into account to prevent unnecessary testing.
• ALT (also referred to as serum glutamic pyruvic transaminase, or SGPT) is an enzyme that may be released into the bloodstream in increased amounts when the liver is damaged by inflammation or other abnormalities.
• AST (also referred to as serum glutamic oxaloacetic transaminase, or SGOT) is an enzyme produced in various organs, including the heart, liver, and skeletal muscle. Increased levels may signal a variety of disorders, including a heart attack; but levels that are exceptionally high--over 500 units--usually indicate liver disease and/or shock.
• Bilirubin is a waste product of red blood cells that is processed in the liver. An excess in the blood can cause a yellowish color (jaundice) in the skin and the whites of the eyes. The levels may be increased as a result of hepatitis, bile duct inflammation, cirrhosis of the liver, liver cancer, and other types of liver disease, as well as by alcoholism, infectious mononucleosis, anorexia, fasting for 36 hours or more, pernicious anemia, pulmonary embolism, and congestive heart failure.
• GGT is an enzyme that is present in bile but also found in blood. Increased GGT levels can signal obstruction of bile ducts, cancer of the liver or pancreas, inflammation of the pancreas, cirrhosis, and hepatitis. Since alcohol increases GGT levels, the enzyme may be measured to monitor abstinence in recovering alcoholics.

It's noninvasive.

It detects the presence of an abnormality but not its cause.

Liver biopsy, imaging studies, or treatment may be recommended depending on the diagnosis.