West Virginia University, Morgantown, USA.
Am Fam Physician. 2011 Nov 15;84(10):1119-26.
Chronic diarrhea, defined as a decrease in stool consistency for more than four weeks, is a common but challenging clinical scenario. It can be divided into three basic categories: watery, fatty (malabsorption), and inflammatory. Watery diarrhea may be subdivided into osmotic, secretory, and functional types. Watery diarrhea includes irritable bowel syndrome, which is the most common cause of functional diarrhea. Another example of watery diarrhea is microscopic colitis, which is a secretory diarrhea affecting older persons. Laxative-induced diarrhea is often osmotic. Malabsorptive diarrhea is characterized by excess gas, steatorrhea, or weight loss; giardiasis is a classic infectious example. Celiac disease (gluten-sensitive enteropathy) is also malabsorptive, and typically results in weight loss and iron deficiency anemia. Inflammatory diarrhea, such as ulcerative colitis or Crohn disease, is characterized by blood and pus in the stool and an elevated fecal calprotectin level. Invasive bacteria and parasites also produce inflammation. Infections caused by Clostridium difficile subsequent to antibiotic use have become increasingly common and virulent. Not all chronic diarrhea is strictly watery, malabsorptive, or inflammatory, because some categories overlap. Still, the most practical diagnostic approach is to attempt to categorize the diarrhea by type before testing and treating. This narrows the list of diagnostic possibilities and reduces unnecessary testing. Empiric therapy is justified when a specific diagnosis is strongly suspected and follow-up is available.
慢性腹泻定义为大便质地变软超过四周，是一种常见但具有挑战性的临床情况。它可以分为三大基本类别：水样便、脂肪泻（吸收不良）和炎症性腹泻。水样便腹泻可进一步分为渗透性、分泌性和功能性腹泻。肠易激综合征是最常见的功能性腹泻病因，属于功能性腹泻。另一种水样便腹泻是显微镜下结肠炎，这是一种影响老年人的分泌性腹泻。刺激性泻药引起的腹泻通常为渗透性腹泻。脂肪泻的特征是排气增多、脂肪泻和体重减轻；贾第虫病是经典的感染性腹泻。乳糜泻（麸质敏感肠病）也是脂肪泻，通常会导致体重减轻和缺铁性贫血。炎症性腹泻，如溃疡性结肠炎或克罗恩病，表现为粪便中有血和脓液，粪便钙卫蛋白水平升高。侵袭性细菌和寄生虫也会引起炎症。由于抗生素使用后产生的艰难梭菌感染，这种炎症性腹泻变得越来越常见，且毒性也越来越强。并非所有慢性腹泻都严格为水样、脂肪泻或炎症性腹泻，因为有些类别存在重叠。因此，在进行检测和治疗之前，通过尝试按类型对腹泻进行分类，是最实用的诊断方法。这可以缩小诊断可能性的范围，减少不必要的检测。当强烈怀疑特定诊断且可进行随访时，经验性治疗是合理的。
