Enzyme specifically raised in chronic alcoholics: September 2009

Ans. D: Ratio of AST: ALT Transferases - Alanine aminotransferase (ALT) or Aspaate aminotransferase (AST): These enzymes normally reside inside cells (in cytoplasm) so raised levels usually represent hepatocellular damage. ALT is more specific to the liver, as AST is also found in cardiac and skeletal muscle and red blood cells. Very high levels (>1000 IU/1) suggest drug induced hepatitis (e.g. paracetamol), acute viral hepatitis (A or B) , ischaemic or rarely autoimmune hepatitis. The ratio of AST to ALT can give some extra clues as to the cause: In chronic liver disease ALT > AST, once cirrhosis established AST > ALT. The extremes of the ratio of AST:ALT can also be helpful: >2 suggests alcoholic liver disease, and a ratio of Gamma-glutamyl transferase (GGT) - also related to the bile ducts. Typically elevated in cholestasis (with elevated ALP), but if ALP normal suggests induction of hepatic metabolic enzymes (e.g alcohol or enzyme inducing drugs). It is not specific to alcohol, easily inducible and is elevated in all forms of fatty liver. Alkaline phosphatase (ALP) - comes mainly from the cells lining bile ducts but also in bone. Marked elevation is typical of cholestasis (often with elevated GGT) or bone disorders (usually normal GGT). Isoenzymes analysis may help identify source. It is physiologically increased when there is increased bone turnover (e.g. adolescence) and is elevated in the third trimester (produced by the placenta).