胰蛋白酶原
快速浏览
为何检测？
通过评估胰腺功能来筛查囊性纤维病和胰腺机能不全。
何时检测？
如果您、您的婴儿有胰腺功能不全或囊性纤维化的症状如持续性腹泻，大块恶臭油脂样粪便，营养不良和维生素缺乏，所以，作为部分新生儿的一般人群筛查和/或如果新生儿患有胎粪性肠梗阻（出生第一个24或48小时内无粪便），则需要做胰蛋白酶原试验。
何种样本？
婴儿足跟采血，滴在滤纸上的血，手臂静脉采血的样本。
是否需要作试验前准备？
不需要。
检测样本
检测什么？
胰蛋白酶原是一种酶原，是胰岛素蛋白水解酶的失活前体。通常，胰蛋白酶原在胰腺中生成并被运输到小肠。在小肠内激活，在肠黏膜内酶的作用下转换成胰岛素，形成强效化学成分使食物中的蛋白质分解成小片段的肽。
有囊性纤维病的患者，宫颈粘液塞能阻断胰腺导管，阻断胰蛋白酶原和糜蛋白酶原进入小肠并妨碍了食物蛋白的分解。可用免疫反应性胰蛋白酶（IRT）来筛查婴儿。患有囊性纤维病几个月的新生儿和正常婴孩血中，任何一过性的胰蛋白酶假阳性升高通常会在几周内降到正常低水平。
在其他疾病中，慢性胰腺炎、胰腺癌和胰腺组织的损伤都可阻断胰蛋白酶原到达小肠。生成胰蛋白酶原的细胞同样会受到损伤或破坏，减少机体的供给。阻塞和细胞损伤都能引起胰腺机能不全。
测试样本如何采集？
可在新生儿或幼小的婴儿的足跟采血，放在滤纸片上或手臂静脉采血。
是否需要进行任何试验前准备以保证样本的质量？
不需要。
试验
有何用途？
免疫反应性胰蛋白酶（IRT）被作为新生儿筛选程序的一部分用来筛查囊性纤维病增加的风险，并辅助诊断小孩和成人的胰腺机能不全。
何时检测？
该试验可作为新生儿是否患有筛查囊性纤维病的一项指标，如当怀疑患有胎粪性肠梗阻时（出生后第一个24或48小时无粪便）时候可以要求检测；当具有囊性纤维病体症的幼小的婴儿未能在汗氯化物试验中留取足够的体汗也可以要求检测。胰蛋白酶原试验还用于小孩或成人出现囊性纤维病和胰腺机能不全体症时，比如持续性腹泻、大块恶臭油脂样粪便、营养不良和维生素缺乏。
胰蛋白酶原试验不是诊断性试验；，除了囊性纤维病（CF）和胰腺机能不全，还存在相当多的假阳性因素和问题能引起IRT阳性。如果该试验结果升高还必须检测其他项目以确诊。当诊断CF时，在一个月内，还须再做一次IRT，并进行CF基因突变测试和/或汗氯化物测试。
试验结果的含义？
假如IRT水平是升高的，婴儿可能患有囊性纤维病；小孩或成人可能有胰酶的异常生成，胰腺炎或胰腺癌；或者这个升高的IRT结果是个假阳性。升高的值需要做进一步的试验。假如IRT水平是阴性但婴儿有体症，应考虑到CF的其他试验如汗氯化物测试或CF基因突变检测。
还有什么我需要了解的吗？
IRT试验不能区别CF突变的杂合子携带者。他们的胰蛋白酶原生成和功能不受影响。患有CF的病人中，IRT水平升高并不反映疾病的严重性。
常见问题
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参考文献
注意：本文是在此处引用的参考文献和医学检验项目在线介绍编辑审核委员会全体成员的经验和研究结果的基础上总结而成。本文由编辑委员会定期审核、更新。任何新引用的文献都会添加到列表中，并且会与原有的参考文献区分开。
Sources Used in Current Review
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Peter Jacky, PhD, FACMG. Director of Cytogenetics and Molecular Genetics, Airport Way Regional Laboratory, Portland, OR.
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Peter Jacky, PhD, FACMG. Director of Cytogenetics and Molecular Genetics, Airport Way Regional Laboratory, Portland, OR.
