Both glutamic and alanine aminotransferases are important for the diagnosis of the disease. Serum levels of glutamate aminotransferase and alanine aminotransferase are a measure of liver cell damage. In normal serum, their levels are low, and if the cells are damaged, this causes the release of intracellular glutamine and glutamine into the bloodstream, causing their concentrations to rise. Glutaminase is found primarily in the liver and to a lesser extent in the kidneys, heart, and skeletal muscle; whereas glutamine is found primarily in the heart and to a lesser extent in the liver, skeletal muscle, and kidney tissues. Thus glutamic aminotransferase is less liver-specific than glutamic aminotransferase, and elevations of glutamic aminotransferase are not limited to liver injury, but can also be seen in times of acute myocardial or skeletal muscle injury. Both are important in the diagnosis of the disease.