Elevated transaminases

In medicine, the presence of elevated transaminases, commonly the transaminases alanine transaminase (ALT) and aspartate transaminase (AST), may be an indicator of liver damage. Other terms employed include transaminasemia, transaminitis (which some sources consider pathologically meaningless) and elevated liver enzymes (though they are not the only enzymes in the liver). Normal ranges for both ALT and AST are 8-40 U/L with mild transaminesemia noted to the upward numerical limit of 250 U/L. Drug-induced increases such as that found with the use of anti-tuberculosis agents such as isoniazid are limited typically to below 100 U/L for either ALT or AST. Cirrhosis of the liver or fulminant liver failure secondary to hepatitis commonly reach values for both ALT and AST in the >1000 U/L range. Elevated transaminases that persist less than six months are termed 'acute' in nature, and those values that persist for six months or more are termed 'chronic' in nature. In medicine, the presence of elevated transaminases, commonly the transaminases alanine transaminase (ALT) and aspartate transaminase (AST), may be an indicator of liver damage. Other terms employed include transaminasemia, transaminitis (which some sources consider pathologically meaningless) and elevated liver enzymes (though they are not the only enzymes in the liver). Normal ranges for both ALT and AST are 8-40 U/L with mild transaminesemia noted to the upward numerical limit of 250 U/L. Drug-induced increases such as that found with the use of anti-tuberculosis agents such as isoniazid are limited typically to below 100 U/L for either ALT or AST. Cirrhosis of the liver or fulminant liver failure secondary to hepatitis commonly reach values for both ALT and AST in the >1000 U/L range. Elevated transaminases that persist less than six months are termed 'acute' in nature, and those values that persist for six months or more are termed 'chronic' in nature. The liver has transaminases to synthesize and break down amino acids and to convert energy storage molecules. The concentrations of these transaminases in the serum (the non-cellular portion of blood) are normally low. However, if the liver is damaged, the liver cell (hepatocyte) membrane becomes more permeable and some of the enzymes leak out into the blood circulation. The two transaminases commonly measured are alanine transaminase (ALT) and aspartate transaminase (AST). These levels previously were called serum glutamate-pyruvate transaminase (SGPT) and serum glutamate-oxaloacetate transaminase (SGOT).Elevated levels are sensitive for liver injury, meaning that they are likely to be present if there is injury. However, they may also be elevated in other conditions such as thyroid disorders, celiac disease, and muscle disorders. ALT is usually found only in the liver. AST is most commonly found in the liver, but also in significant amounts in heart (cardiac) and skeletal muscle. Measurement of ALT and AST were used in diagnosing heart attacks, although they have been replaced by newer enzyme and protein tests that are more specific for cardiac damage.