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 dysfunction. Other terms include transaminasemia, transaminitis, and elevated liver enzymes (though they are not the only enzymes in the liver). Normal ranges for both ALT and AST vary by gender, age, and geography and are roughly 8-40 U/L (0.14-0.67 μkal/L). Mild transaminesemia refers to levels up to 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. Muscle sources of the enzymes, such as intense exercise, are unrelated to liver function and can markedly increase AST and ALT. 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.