Macro-AST in an asymptomatic young patient

Chtioui, Haïthem; Mauerhofer, Olivier; Günther, B; Dufour, Jean‐François

doi:10.1016/s1665-2681(19)31687-4

Cited by 18 publications

(20 citation statements)

References 10 publications

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“…Contradictory to our findings, Chtioui et al 11 reported that a serum sample from their patient with macro-AST did not show any decrease in AST activity after storage at 4°C for 1 week. This discrepancy may be due to the heterogeneity of the macro-AST molecule implicated by the different types of immunoglobulins or other plasma components.…”

Section: Discussionsupporting

confidence: 63%

<p>Importance Of Laboratory Detection Of Macro-Aspartate Aminotransferase</p>

Ono¹,

Kurata²,

Nishimura³

et al. 2019

IJGM

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The macroenzyme form of aspartate aminotransferase (macro-AST) is formed by the binding of AST with immunoglobulins. Macro-AST excretion from serum is prolonged because of its high molecular weight, leading to increased AST activities. Because of the difficulty in detecting macro-AST through routine laboratory tests, affected patients often undergo repeated examinations, with associated anxiety. We report a case in which macro-AST was detected by assaying the patient's serum after refrigeration at 4ºC for 3 days. The sample showed progressive loss of AST activity compared with that frozen in the refrigerator, indicating the presence of macro-AST, which was confirmed as a complex with IgG-κ. The cold storage method was validated using many samples obtained from several patients. Use of this simple method to detect macro-AST may avoid unnecessary examinations and patient anxiety even at primary care facilities.

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Section: Discussionsupporting

confidence: 63%

<p>Importance Of Laboratory Detection Of Macro-Aspartate Aminotransferase</p>

Ono¹,

Kurata²,

Nishimura³

et al. 2019

IJGM

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show abstract

“…Macro‐AST is a rare phenomenon of unknown pathogenesis with only a few cases reported in literature, prevalence seems to be lower than other form of macro‐enzymes like creatin kinase, lactate dehydrogenase or amylase . The presence of macro‐AST as other macro‐enzymes is generally considered a benign process, however long‐term effects on the patient or association with other pathologies are still unknown …”

Section: Discussionmentioning

confidence: 99%

Isolated elevation of aspartate aminotransferase (AST) in an asymptomatic patient due to macro‐AST

Raya

Zuñiga

Sálido

2018

Clinical Laboratory Analysis

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Background A rare and benign cause of isolated aspartate aminotransferase (AST) increase is due to the presence of macro aspartate aminotransferase (macro‐AST). Macro‐AST is not usually considered by clinicians, leading to a large number of unnecessary and even invasive tests before diagnosed. Most commonly used laboratory methods for detection of macro‐enzymes are precipitation with polyethylene glycol (PEG), ultracentrifugation and gel filtration chromatography (GFC). Methods We report a case of an asymptomatic patient with persistent isolated AST elevation. PEG precipitation and an alternative method based on the low stability of this macro‐enzyme were performed on the patient serum. Results Macro‐AST was early detected by the laboratory observing a significant decrease in AST concentrations when the serum is stored at 4ºC. Conclusions Macro‐AST detection based in this method can be very useful as screening, especially in those laboratories where other technologies are not available. Macro‐AST must be considered as cause of unexplained isolated AST elevations before prior investigations to avoid the consequent cost and potential harm to the patient. In our case, early detection of macro‐AST with this method avoided unnecessary treatment and invasive test such as liver biopsy.

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“…Macro-AST can be detected by multiple methods; the most common are precipitating the complexes of macroenzymes with PEG or simply storing the sample at 4 ºC, which is convenient and economical, although two cases reported by Chtioui et al[14] in 2010 and Maan et al[15] in 2017 showed no significant decrease in AST levels after 1 wk of being stored at 4 ºC. Ultracentrifugation and gel filtration chromatography, which constitute the standard reference method, require highly specialized chromatography, are complex and relatively expensive and are not available in most clinical laboratories.…”

Section: Discussionmentioning

confidence: 99%

Isolated elevated aspartate aminotransferase in an asymptomatic woman due to macro-aspartate aminotransferase: A case report

Zhan¹,

Liu²,

Zhang³

et al. 2019

WJCC

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BACKGROUNDMacro-aspartate aminotransferase (AST), a macroenzyme, is a high-molecular mass complex formed by self-polymerization or association with other serum components that are difficult for the kidney to clear, leading to the isolated elevation of serum AST activity. Cases of macro-AST formation are rare, with only 3 published in the English language literature up to September 2019 in China. In this paper, we present a case in which an asymptomatic woman with persistent isolated elevated AST was confirmed as having macro-AST by the polyethylene glycol precipitation method.CASE SUMMARYA 34-year-old woman was referred to our clinic for elevated AST levels with normal levels of other liver-associated enzymes on November 12, 2018. Her AST level of liver function test had been abnormal for 7 mo before she came to the clinic. The patient was asymptomatic with a normal physical examination. There was no relevant family history and no alcohol consumption or smoking. She had a several-month history of traditional Chinese medical taking and had stopped it 1 year prior. The laboratory tests in our clinic showed only the elevation of AST (89.5 U/L) with no other significant abnormalities. We performed the precipitation technique with polyethylene glycol to confirm the presence of macro-AST. Then for almost a year, her AST level still fluctuated in the abnormal range.CONCLUSIONThis case highlights that clinical physicians should be familiar with this rare condition of persistent isolated AST elevation due to the presence of macro-AST to avoid unnecessary investigation and patient anxiety.

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Macro-AST in an asymptomatic young patient

Cited by 18 publications

References 10 publications

<p>Importance Of Laboratory Detection Of Macro-Aspartate Aminotransferase</p>

<p>Importance Of Laboratory Detection Of Macro-Aspartate Aminotransferase</p>

Isolated elevation of aspartate aminotransferase (AST) in an asymptomatic patient due to macro‐AST

Isolated elevated aspartate aminotransferase in an asymptomatic woman due to macro-aspartate aminotransferase: A case report

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