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Gastroenterologie
a hepatologie

Gastroenterology and Hepatology

Gastroent Hepatol 2016; 70(2): 138– 140. doi:10.14735/amgh2016138.

Macro-AST as a cause of isolated chronically elevated AST activity – two case reports

Irena Hejlová Orcid.org  1, Jitka Komrsková2, Eva Sticová Orcid.org  3, Pavel Trunečka4, Julius Špičák Orcid.org  1, Janka Franeková2

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Summary

Introduction: Some enzymes, e.g., aspartate aminotransferase (AST), can form high molecular mass complexes, referred to as macro enzymes, which persist in the serum and cause increased serum activity. Case study: We describe two cases of isolated chronically elevated AST activity in two young asymptomatic females (20- and 21-years-old). Both patients denied alcohol consumption, use of medication, or increased muscle activity. ALT activity and other initial laboratory studies were normal.  Detailed investigation did not reveal any disease of liver, muscles, heart, or thyroid gland, or the presence of celiac disease. This led us to consider the possibility of macro-AST. A polyethylene glycol precipitation assay was performed, which revealed 92% and 79% polyethylene glycol precipitable activity, confirming the presence of macro-AST in both patients. Conclusion: Isolated chronically elevated AST activity may be caused by the presence of macro-AST. Confirmation of macro-AST positivity may help avoid expensive and invasive investigations.

Keywords

AST, aspartate aminotransferase, macro-AST, macroenzymes

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Literature

1. Pratt DS, Kaplan MM. Evaluation of abnormal liver-enzyme results in asymptomatic patients. N Engl J Med 2000; 342 (17): 1266–1271.
2. Caropreso M, Fortunato G, Lenta S et al. Prevalence and long-term course of macro-aspartate aminotransferase in children. J Pediatr 2009; 154 (5): 744–748. doi: 10.1016/j.jpeds.2008.11.010.
3. Lee M, Vajro P, Keeffe EB. Isolated aspartate aminotransferase elevation: think macro-AST. Dig Dis Sci 2011; 56 (2): 311–313.
4. Davidson DF, Watson DJ. Macroenzyme detection by polyethylene glycol precipitation. Ann Clin Biochem 2003; 40 (5): 514–520.
5. Manns MP, Czaja AJ, Gorham JD et al.  Diagnosis and management of autoimmune hepatitis. Hepatology 2010; 51 (6): 2193–2213. doi: 10.1002/hep.23584.
6. Moriyama T, Tamura S, Nakano K et al. Laboratory and clinical features of abnormal macroenzymes found in human sera. Biochim Biophys Acta 2015; 1854 (6): 658–667. doi: 10.1016/j.bbapap.2014.10.015.
7. Patteet L, Simoens M, Piqueur M et al. Laboratory detection of macro-aspartate aminotransferase: case report and evaluation of the PEG-precipitation method. Clin Biochem 2012; 45 (9): 691–693. doi: 10.1016/j.clinbiochem.2012.03.004.
8. Briani C, Zaninotto M, Forni M et al. Macroenzymes: too often overlooked. J Hepatol 2003; 38 (1): 119.
9. Moriyama T, Nobuoka M, Makino M. Incidence and properties of aspartate aminotransferase-immunoglobulin complexes in patients with a high serum aspartate to alanine aminotransferase ratio. Clin Chim Acta 1990; 190 (1–2): 47–56.
10. Smolka V, Kamarýt J, Hrabincová E et al. Makroforma enzymu aspartátaminotransferázy u zdravých dětí jako benigní příčina vysoké sérové aktivity AST. Čs Pediat 1998; 53 (3): 152–155.
11. Orlando R, Carbone A, Lirussi F. Macro-aspartate aminotransferase (macro-AST). A 12-year follow-up study in a young female. Eur J Gastroenterol Hepatol 2003; 15 (12): 1371–1373.
12. Yu Z, Wang Y, Feng L et al. Macro-aspartate aminotransferase: two-year follow-up of three patients in China. Dig Dis Sci 2014; 59 (1): 224–226. doi: 10.1007/s10620-013-2856-x.
13. Slabík D, Freiberger T, Tomašovičová Z et al. Makrokomplex AST jako příčina nejasné elevace sérové aktivity AST. Klin Biochem Metab 2004; 12 (33): 42–45.

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