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Chapter 040. Diarrhea and Constipation (Part 10)

Postmucosal Lymphatic Obstruction The pathophysiology of this condition, which is due to the rare congenital intestinal lymphangiectasia or to acquired lymphatic obstruction secondary to trauma, tumor, or infection, leads to the unique constellation of fat malabsorption with enteric losses of protein (often causing edema) and lymphocytopenia. Carbohydrate and amino acid absorption are preserved. INFLAMMATORY CAUSES Inflammatory diarrheas are generally accompanied by pain, fever, bleeding, or other manifestations of inflammation. The mechanism of diarrhea may not only be exudation but, depending on lesion site, may include fat malabsorption, disrupted fluid/electrolyte absorption, and hypersecretion or hypermotility from release of cytokines and other inflammatory mediators | Chapter 040. Diarrhea and Constipation Part 10 Postmucosal Lymphatic Obstruction The pathophysiology of this condition which is due to the rare congenital intestinal lymphangiectasia or to acquired lymphatic obstruction secondary to trauma tumor or infection leads to the unique constellation of fat malabsorption with enteric losses of protein often causing edema and lymphocytopenia. Carbohydrate and amino acid absorption are preserved. INFLAMMATORY CAUSES Inflammatory diarrheas are generally accompanied by pain fever bleeding or other manifestations of inflammation. The mechanism of diarrhea may not only be exudation but depending on lesion site may include fat malabsorption disrupted fluid electrolyte absorption and hypersecretion or hypermotility from release of cytokines and other inflammatory mediators. The unifying feature on stool analysis is the presence of leukocytes or leukocyte-derived proteins such as calprotectin. With severe inflammation exudative protein loss can lead to anasarca generalized edema . Any middle-aged or older person with chronic inflammatory-type diarrhea especially with blood should be carefully evaluated to exclude a colorectal tumor. Idiopathic Inflammatory Bowel Disease The illnesses in this category which include Crohn s disease and chronic ulcerative colitis are among the most common organic causes of chronic diarrhea in adults and range in severity from mild to fulminant and life-threatening. They may be associated with uveitis polyarthralgias cholestatic liver disease primary sclerosing cholangitis and skin lesions erythema nodosum pyoderma gangrenosum . Microscopic colitis including both lymphocytic and collagenous colitis is an increasingly recognized cause of chronic watery diarrhea especially in middle-aged women and those on NSAIDS biopsy of a normal-appearing colon is required for histologic diagnosis. It may coexist with symptoms suggesting IBS or with celiac sprue. It typically responds well to anti inflammatory drugs .