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Persistent AST Elevation in a Patient With Ovarian Cancer: A Rare Diagnostic Challenge
Lechuang Chen1, Yu Zhang1, Qing H Meng1
1Department of Laboratory Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Journal of Clinical Laboratory Analysis
|June 24, 2025
Summary
Persistent isolated aspartate aminotransferase (AST) elevation can be caused by macro-AST, a rare condition where AST binds to immunoglobulins. Identifying macro-AST prevents unnecessary tests for liver disease.
Area of Science:
- Biochemistry
- Clinical enzymology
Background:
- Persistent isolated aspartate aminotransferase (AST) elevation often suggests liver injury but can be challenging to diagnose.
- AST is a non-specific enzyme found in various tissues, and its isolated elevation points to less common causes like macro-AST.
Observation:
- A 68-year-old female with high-grade serous ovarian cancer presented with persistent isolated AST elevation over several years.
- Extensive evaluations, including physical exams, imaging, and liver function tests, ruled out hepatic or muscular disease.
- Polyethylene glycol (PEG) precipitation markedly decreased serum AST activity, confirming macro-aspartate aminotransferase (macro-AST).
Findings:
- This case documents a rare instance of macro-AST in a patient with ovarian cancer.
- Macro-AST is characterized by AST binding with immunoglobulins, forming a high-molecular-weight complex that alters enzyme activity.
Implications:
- Considering macro-AST in the differential diagnosis of isolated AST elevation is crucial, especially in patients without apparent liver or muscle disease.
- Recognition of this benign condition can avert unnecessary diagnostic procedures and patient anxiety.
- This finding underscores the importance of specific diagnostic tests for atypical enzyme elevations.
