Persistently high serum aspartate aminotransferase level in an asymptomatic young patient.

Key Clinical Message: We report a young man with isolated elevated AST. He had no other evidence of liver or other related diseases. All the tests and examination reports were negative. The final diagnosis of macro-AST was confirmed by PEG precipitation tests. Abstract: Elevated liver enzymes, such as alanine aminotransferase (ALT) and aspartate aminotransferase (AST), may commonly indicate liver injury. However, macro-AST is generally a benign condition that may be considered as pathologic by clinicians. A young man with isolated elevated AST for more than 10 years who have taken extensive tests and examinations was diagnosed with macro-AST in our article. Thus, in patients with isolated AST-elevation, polyethylene glycol (PEG) precipitation test was recommended to test whether macro-AST could be diagnosed.