AIM To review stool diagnostic tests in acute and chronic diarrhea. METHOD Narrative review of published literature. RESULTS (A). In acute diarrhea, stool tests are indicated when there is strong pre-test probability of infectious etiology or C. difficile infection (CDI) suggested by >3 unformed bowel movements per 24h, symptoms lasting >7 days, and circumstances that are suggestive of infection. Several commercially available rapid tests for bacterial, viral or protozoal infections may be offered in addition to traditional methods (e.g. culture, microscopy), and provide a result within 6 hours. For CDI infection, a highly sensitive test such as glutamate dehydrogenase test is required; however, this does not distinguish infection from carrier state. That differentiation requires specialized nucleic acid amplification test (for toxin B) or enzyme immunoassays for toxin A or B, which are unfortunately not generally offered by microbiology labs. (B). Chronic diarrhea may result from inflammatory, fatty, osmotic or secretory causes; the commonest causes are IBS-D/functional diarrhea. Current recommendations in societal guidelines or clinical practice updates regarding stool tests in IBS-D/functional diarrhea in the absence of alarm symptoms include testing for giardia, calprotectin, fecal immunochemical test (FIT), and bile acid diarrhea (BAD). Comprehensive stool biochemical analyses (osmolality, pH, electrolytes) differentiate osmotic from secretory diarrhea and identify laxative abuse. Specific stool diagnostic tests for BAD and exocrine pancreatic insufficiency can lead to specific diagnosis and treatments. Surrogate markers associated with high fecal output and rapid transit in chronic diarrhea are stool form and colonic transit. CONCLUSION Fecal testing is still very relevant in the practice of gastroenterology and deserves introduction of advanced microbiological and biochemical tests.

中文翻译：

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何时以及检查什么腹泻：重点检查粪便。


目的 评价急性和慢性腹泻的粪便诊断试验。方法 已发表文献的叙述性回顾。结果 （A）。在急性腹泻中，当每 24 小时有 >3 不成形排便、症状持续 >7 天以及提示感染的情况提示感染性病因或艰难梭菌感染 （CDI） 的验前可能性很高时，需要进行粪便检查。除了传统方法（例如培养、显微镜检查）外，还可以提供几种市售的细菌、病毒或原生动物感染快速检测，并在 6 小时内提供结果。对于 CDI 感染，需要进行高敏感性测试，例如谷氨酸脱氢酶测试;然而，这并不能区分感染和携带者状态。这种区分需要专门的核酸扩增检测（针对毒素 B）或针对毒素 A 或 B 的酶免疫测定，不幸的是，微生物学实验室通常不提供这些检测。慢性腹泻可能由炎症、脂肪、渗透性或分泌性原因引起;最常见的原因是 IBS-D/功能性腹泻。目前社会指南或临床实践更新中关于在没有警报症状的情况下对 IBS-D/功能性腹泻进行粪便检测的建议包括贾第鞭毛虫、钙卫蛋白、粪便免疫化学检测 （FIT） 和胆汁酸腹泻 （BAD）。全面的粪便生化分析（渗透压、pH 值、电解质）可区分渗透性腹泻和分泌性腹泻，并识别泻药滥用。针对 BAD 和胰腺外分泌功能不全的特异性粪便诊断测试可导致特异性诊断和治疗。在慢性腹泻中，与高粪便排出量和快速转运相关的替代标志物是粪便形态和结肠转运。 结论粪便检测在胃肠病学实践中仍然非常重要，值得引入先进的微生物学和生化检测。