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.