Distribution of serum concentrations reported for macroenzyme aspartate aminotransferase (macro-AST)

Abstract

BackgroundThe presence of macroenzyme (M) is often the explanation of an isolated elevation of aspartate aminotransferase (AST). Where M is identified, it is reasonable for the clinician to ask where an individual patient's result fits in with known concentrations of M. In this context, we conducted a survey of literature to examine the distribution of reported serum concentrations of macro-AST. We also analyzed the distribution data to examine whether elevations were consistent with simple alteration of circulatory half-life (t1/2) of M relative to normal AST.MethodsDistributions of M were compiled from the literature. These distributions were compared to predictions based on fixed changes in t1/2 applied to the reference interval for AST.ResultsThere was a bimodal distribution of literature values for M (n =51), comprised roughly of populations A (M <200 U/L; 60% of total) and B (M >200 U/L; 40% of total). The two distributions were reasonably well characterized by a simple projection to the right of the reference interval for AST according to increased t1/2 (A: t1/2 =3.3 days; B: t1/2 =19.8 days) relative to AST (t1/2 =0.7 days).ConclusionsKnowledge of distributions for M may be useful in discussion with clinicians regarding significance of M for individual patients. Distributions for M were consistent with the simplest explanation for elevated AST due strictly to an extended circulatory lifetime for M. Caveats to analysis, however, include selection within literature data mainly for patients with various co-morbidities.

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

“…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 …”

A case of macroenzyme aspartate aminotransferase (macro-AST) in a patient with seronegative rheumatoid arthritis

“…Immunoglobulin G (IgG), immunoglobulin A (IgA) and immunoglobulin M (IgM) bound to AST have all been described. [1][2][3][4][5][6][7][8] Macro-AST is generally benign.…”

Reduction of hepatotoxicity of nimesulide in mechanochemically obtained composition with disodium salt of glycyrrhizic acid

“…4). Можно предположить, что это является проявлением феномена «макроэнзимов», в частности -макро-АсАТ, описанного в ряде клинических случаев [22][23][24][25][26]. В настоящее время не существует адекватного объяснения данного феномена, однако авторы отмечают, что он не связан ни с заболеваниями печени, ни с заболеваниями сердца.…”