Persistent AST Elevation in a Patient With Ovarian Cancer: A Rare Diagnostic Challenge

Lechuang Chen ¹, Yu Zhang ¹, Qing H Meng ¹

⁰Department of Laboratory Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.

Journal of Clinical Laboratory Analysis +

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June 24, 2025

View abstract on PubMed

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.

Keywords:

AST elevation PEG precipitation cancer macro‐AST