ARUP Institute for Clinical and Experimental Pathology, Salt Lake City, UT 84108, USA.
Clin Chim Acta. 2011 Nov 20;412(23-24):2052-7. doi: 10.1016/j.cca.2011.01.023. Epub 2011 Jan 26.
Macroenzymes may cause elevations in serum enzyme activity. Macroenzymes are not common; however their detection is important because they cause diagnostic confusion and therapeutic errors.
We analyzed 2 of the most prevalent macroenzymes in the literature, macro-creatine kinase (macro-CK) and macroamylase, using 2 methods for detection, polyethylene glycol (PEG) precipitation and ultrafiltration (UF). Enzyme measurements were made using a Roche Modular Analytics P analyzer. Imprecision was assessed using quality control material. We evaluated 125 samples from apparently healthy subjects to establish reference intervals. For macro-CK comparison, 94 samples with activities >200 U/l were analyzed with both PEG precipitation and UF and compared to electrophoresis. PEG precipitation and UF were compared for macroamylase detection using 130 samples with amylase activities >110 U/l.
UF was more precise and demonstrated narrower reference intervals for both analytes. PEG precipitation and UF were able to detect true cases of macro-CK with overall agreement with electrophoresis of 79.8% and 80.9%, respectively. Both methods detected the same number of 'positive' macroamylase samples; however PEG precipitation resulted in a greater number of 'indeterminate' cases.
This is the first report where UF has been shown useful for the detection of both macro-CK and macroamylase.
巨酶可能导致血清酶活性升高。巨酶并不常见；然而，它们的检测很重要，因为它们会导致诊断混淆和治疗错误。
我们使用两种检测方法——聚乙二醇（PEG）沉淀法和超滤法（UF），分析了文献中最常见的两种巨酶，即巨肌酸激酶（macro-CK）和巨淀粉酶。使用罗氏 Modular Analytics P 分析仪进行酶测定。使用质控材料评估不精密度。我们评估了 125 名来自健康受试者的样本，以建立参考区间。为了比较 macro-CK，我们分析了 94 例活性>200 U/l 的样本，分别用 PEG 沉淀法和 UF 法与电泳法进行比较。使用 130 例淀粉酶活性>110 U/l 的样本，比较了 PEG 沉淀法和 UF 法检测巨淀粉酶的效果。
UF 对两种分析物的精密度更高，且参考区间更窄。PEG 沉淀法和 UF 法均能检测到真正的 macro-CK 病例，与电泳法的总符合率分别为 79.8%和 80.9%。两种方法检测到的“阳性”巨淀粉酶样本数量相同；然而，PEG 沉淀法导致更多的“不确定”病例。
这是首次报道 UF 对检测 macro-CK 和巨淀粉酶均有用。
