González Raya Arturo, Coca Zúñiga Ramón, Martín Salido Eva
Department of Clinical Laboratory, University Hospital Center Virgen de las Nieves, Granada, Spain.
Department of Clinical Laboratory, Costa del Sol Hospital, Marbella, Spain.
J Clin Lab Anal. 2019 Feb;33(2):e22690. doi: 10.1002/jcla.22690. Epub 2018 Oct 15.
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).
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.
Macro-AST was early detected by the laboratory observing a significant decrease in AST concentrations when the serum is stored at 4ºC.
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.
孤立性天冬氨酸氨基转移酶（AST）升高的一种罕见良性病因是巨天冬氨酸氨基转移酶（macro-AST）的存在。临床医生通常不会考虑到macro-AST，这导致在诊断前进行大量不必要甚至有创的检查。检测巨酶最常用的实验室方法是聚乙二醇（PEG）沉淀法、超速离心法和凝胶过滤色谱法（GFC）。
我们报告一例无症状患者持续性孤立性AST升高的病例。对患者血清进行PEG沉淀以及基于这种巨酶低稳定性的另一种方法检测。
实验室通过观察血清在4℃保存时AST浓度显著降低，早期检测到了macro-AST。
基于这种方法的macro-AST检测作为筛查可能非常有用，尤其是在那些没有其他技术的实验室。在进行进一步检查之前，必须将macro-AST视为不明原因孤立性AST升高的病因，以避免随之而来的费用以及对患者的潜在危害。在我们的病例中，用这种方法早期检测到macro-AST避免了不必要的治疗和肝活检等有创检查。
