Unexplained High Activity of Aspartate Aminotransferase in an Asymptomatic Pediatric Patient

Authors

1 Department of Pediatrics, Golisano Children's Hospital, Upstate Medical University, Syracuse, NY, USA.

2 University of California and San Francisco, Department of Epidemiology and Biostatistics, San Francisco, CA, USA.

3 Pediatric Gastroenterology, Hepatology and Nutrition, Golisano Children's Hospital, Upstate Medical University, Syracuse, NY, USA.

Abstract

Elevated enzyme activities in plasma may at times be attributed to the presence of macro-enzymes. The macro-enzymes are often serum enzymes in complex with immunoglobulins, resulting in a greater molecular mass that cannot be filtered by renal glomeruli and are, hence, retained in the plasma. The aspartate aminotransferase (AST) can exist as a macro-enzyme, although it has been rarely reported.
We describe a pediatric patient with persistently elevated serum AST activity, due to macro-enzyme formation between AST and an immunoglobulin. This is to highlight the importance of early diagnosis of macro-AST in an otherwise asymptomatic pediatric patient with isolated AST-elevation and to avoid unnecessary costly testing.

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