Liver Function Test (LFT)

Submitted by Nic on October 18, 2012

The human liver carries out a number of tasks that help the body to absorb the nutrients from the food it consumes and also to eliminate various toxins from the body. A liver function test or LFT test is an effective tool to gauge the functioning of the liver. Various proteins and enzymes made in the liver are present in the blood, and LFT testing to measure the level of a particular enzyme or protein in the blood can be used to confirm a doctor's diagnosis of a specific type of liver disease. Certain enzymes are released into the blood stream when the liver cells are damaged, and an LFT test report showing the presence and the levels of these enzymes in the blood facilitates in the selection of the right course of treatment.

Usually, an LFT blood test measures the amount of bilirubin in the blood. Bilirubin is released when red blood cells breakdown, and it is the liver that detoxifies the bilirubin and helps to eliminate it from the body. Bilirubin is a part of the digestive juice, bile, which the liver produces. In cases of liver illnesses like hepatitis, bilirubin levels in the blood may be elevated. Also, a low level of albumin, a protein which is made by the liver, is an indication of liver distress. The total protein measures the levels of albumin and globulin in the blood to assess liver function.

Enzymes such as alanine transaminase (ALT), produced by liver cells, and aspartate transaminase (AST) in the blood are monitored, as high levels of ALT usually indicate liver cell damage. LFT test normal range levels are below 35 for both enzymes, while an elevated ALT is a cause for concern. AST can be found in several organs of the body, and so is not considered liver-specific. Gamma glutamyl transpeptidase or GGT is an enzyme produced in the bile duct. The LFT test range of someone who abuses alcohol or is treated with drugs that are toxic to the liver may show high levels of GGT even when there is minimal damage to the liver. In other patients, it is considered a useful indicator of bile duct disease. Alkaline phosphatase, also referred to ALK Phos, is another enzyme that points to bile duct illness when it is seen in elevated levels in the blood.

LFT test cost may be lower than that of imaging tests like CAT scans or MRI scans, but doctors find the test to be useful tool in identifying the type of liver disease that needs to be treated.

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