In Reply. —
Mandell's comments regarding "liver enzyme" abnormalities in patients with diseases causing skeletal muscle damage are appreciated. There is no question that patients with clinical signs of myositis or muscle trauma can have elevations in the alanine aminotransferase (ALT) level, although generally much lower levels than those of aspartate aminotransferase (AST) activity. The relative tissue enzyme activity ratio of AST to ALT in skeletal muscle is reported to be 16.6:1, while in the liver it is 22.214.171.124 In the absence of muscular pain symptoms, I feel that it is much less likely that abnormalities in the ALT level will be associated with a skeletal muscle etiology. Distance runners frequently have increased AST levels (up to 2 times normal) and elevated creatine phosphokinase levels due to skeletal muscle trauma, but the ALT level tends to be normal in this group.2,3 It is for this reason that I discourage sole
Sherman KE. Alanine Aminotransferase:: A Nonspecific Marker of Liver Disease-Reply. Arch Intern Med. 1992;152(1):213. doi:10.1001/archinte.1992.00400130197039
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