ALT, AST & Total Bilirubin

ALT (alanine aminotransferase) is measured to see if the liver is damaged or diseased. Low levels of ALT are normally found in the blood. But when the liver is damaged or diseased, it releases ALT into the bloodstream, which makes ALT levels go up.

AST (aspartate aminotransferase) are normally found in the blood. When body tissue or an organ such as the heart or liver is diseased or damaged, additional AST is released into the bloodstream. The amount of AST in the blood is directly related to the extent of the tissue damage.

The AST test may be done at the same time as a test for ALT. The ratio of AST to ALT sometimes can help determine whether the liver or another organ has been damaged.

Bilirubin (formerly referred to as hematoidin) is the yellow breakdown product of normal heme catabolism. Heme is found in hemoglobin, a principal component of red blood cells. Bilirubin is excreted in bile, and its levels are elevated in certain diseases. It is responsible for the yellow color of bruises and the yellow discoloration in jaundice.

 

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