Solving the mystery of persistent isolated aspartate aminotransferase elevation: Macro-AST as a decisive diagnostic consideration
- 1Center of Integrative Medicine, Beijing Ditan Hospital, Capital Medical University , ,
- 2Department of Pathology, Beijing Ditan Hospital, Capital Medical University , ,
Abstract
Background
Persistent isolated elevation of aspartate aminotransferase (AST) often poses a diagnostic challenge. Macro-AST, though underrecognized, is a benign cause that may avoid unnecessary investigations.Aim
To characterize the clinical and laboratory features of macro-AST in Chinese adults and to describe our experience with the PEG precipitation method in identifying this condition.Methods
Clinical data from patients presenting with persistent isolated AST elevation at Beijing Ditan Hospital, Capital Medical University, between February and August 2025 were analyzed. All patients underwent comprehensive laboratory tests (including routine biochemistry, muscle enzymes and autoantibodies), imaging studies (abdominal ultrasound and transient elastography), and liver biopsy. After excluding other definitive diseases, macro-AST was confirmed using the PEG precipitation method. Sera from one healthy control and one disease control (with chronic active hepatitis B) were also collected.Results
Three patients (2 female, 1 male) were confirmed with macro-AST. Immunological evaluation revealed heterogeneous serological features among the three patients, including positive autoantibodies and variably elevated immunoglobulin levels in a subset of cases. The persistent isolated AST elevation was not adequately explained by any histological finding. Following PEG precipitation, the AST recovery rate was considerably lower in macro-AST patients (mean 9.71% ± 6.29%; individual values: 2.02%, 17.42%, and 9.68%) than in the healthy control (88.10%) and the disease control with chronic active hepatitis B (59.63%), while PPA% was markedly higher in macro-AST patients (mean 90.29% ± 6.28%; individual values: 97.97%, 82.58%, and 90.32%) than in the healthy control (11.90%) and the disease control (40.37%).Conclusion
Macro-AST should be considered in cases of persistent isolated AST elevation with unremarkable workup. Testing for macro-AST by PEG precipitation should be considered before proceeding to invasive procedures such as liver biopsy. In this study, the PEG precipitation method proved to be a practical adjunctive tool for identifying macro-AST, although its reliability and diagnostic accuracy in a wider population remain to be confirmed.
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BibTeX
@article{sun2026solving,
title = {{Solving the mystery of persistent isolated aspartate aminotransferase elevation: Macro-AST as a decisive diagnostic consideration}},
author = {Lina Sun and Yao Liu and Xue Yang and Fangyuan Gao and Lei Sun and Yu Lu and Yanqiu Li and Ying Feng and Xianbo Wang},
journal = {Frontiers in cellular and infection microbiology},
year = {2026},
month = oct,
doi = {10.3389/fcimb.2026.1895517},
url = {https://europepmc.org/article/PMC/PMC13718027},
note = {CC BY},
}
RIS
TY - JOUR
TI - Solving the mystery of persistent isolated aspartate aminotransferase elevation: Macro-AST as a decisive diagnostic consideration
AU - Lina Sun
AU - Yao Liu
AU - Xue Yang
AU - Fangyuan Gao
AU - Lei Sun
AU - Yu Lu
AU - Yanqiu Li
AU - Ying Feng
AU - Xianbo Wang
PY - 2026
DA - 2026/10/07
JO - Frontiers in cellular and infection microbiology
DO - 10.3389/fcimb.2026.1895517
UR - https://europepmc.org/article/PMC/PMC13718027
AB - Background Persistent isolated elevation of aspartate aminotransferase (AST) often poses a diagnostic challenge. Macro-AST, though underrecognized, is a benign cause that may avoid unnecessary investigations.Aim To characterize the clinical and laboratory features of macro-AST in Chinese adults and to describe our experience with the PEG precipitation method in identifying this condition.Methods Clinical data from patients presenting with persistent isolated AST elevation at Beijing Ditan Hospital, Capital Medical University, between February and August 2025 were analyzed. All patients underwent comprehensive laboratory tests (including routine biochemistry, muscle enzymes and autoantibodies), imaging studies (abdominal ultrasound and transient elastography), and liver biopsy. After excluding other definitive diseases, macro-AST was confirmed using the PEG precipitation method. Sera from one healthy control and one disease control (with chronic active hepatitis B) were also collected.Results Three patients (2 female, 1 male) were confirmed with macro-AST. Immunological evaluation revealed heterogeneous serological features among the three patients, including positive autoantibodies and variably elevated immunoglobulin levels in a subset of cases. The persistent isolated AST elevation was not adequately explained by any histological finding. Following PEG precipitation, the AST recovery rate was considerably lower in macro-AST patients (mean 9.71% ± 6.29%; individual values: 2.02%, 17.42%, and 9.68%) than in the healthy control (88.10%) and the disease control with chronic active hepatitis B (59.63%), while PPA% was markedly higher in macro-AST patients (mean 90.29% ± 6.28%; individual values: 97.97%, 82.58%, and 90.32%) than in the healthy control (11.90%) and the disease control (40.37%).Conclusion Macro-AST should be considered in cases of persistent isolated AST elevation with unremarkable workup. Testing for macro-AST by PEG precipitation should be considered before proceeding to invasive procedures such as liver biopsy. In this study, the PEG precipitation method proved to be a practical adjunctive tool for identifying macro-AST, although its reliability and diagnostic accuracy in a wider population remain to be confirmed.
SN - 2235-2988
ER -