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SOURCE

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Source: Hemstreet BA. Inflammatory bowel disease. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 10th ed. New York, NY: McGraw-Hill; 2017. http://accesspharmacy.mhmedical.com/content.aspx?bookid=1861&sectionid=146059124. Accessed April 14, 2017.

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DEFINITION

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  • Idiopathic inflammatory bowel disease (IBD) manifesting as transmural inflammation of gastrointestinal (GI) mucosa.

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ETIOLOGY

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  • Unknown, but major theories include combination of infectious, genetic, and immunologic causes.

    • Infectious.

      • Viruses.

      • Protozoa.

      • Mycobacteria (eg, Mycobacterium paratuberculosis or avium)

      • Listeria monocytogenes

      • Chlamydia trachomatis

      • Escherichia coli

      • Ruminococcus gnavus or torques

    • Genetics.

      • Gene defects (eg, nucleotide-binding oligomerization domain protein 2 (NOD2), ATG16L1, IRGM, polymorphisms of the IL-23 receptor IL-23R, and IL-12B, STAT3, and CCR6)

    • Immune.

      • Immune-mediated mucosal damage.

      • Dysregulation of cytokines.

    • Psychological.

      • Stress.

      • Anxiety and depression.

    • Lifestyle.

      • Smoking.

    • Diet.

      • Intake of refined sugars.

      • Diets low in fruits and vegetables and high in ω-6 polyunsaturated fats.

      • Vitamin D deficiency.

    • Drugs.

      • Nonsteroidal anti-inflammatory drugs (NSAIDs)

      • Oral contraceptives.

      • Isotretinoin.

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PATHOPHYSIOLOGY

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  • Transmural inflammatory process most commonly seen in terminal ileum.

    • Discontinuous disease with normal bowel separating segments of diseased bowel.

    • Comparison with ulcerative colitis (UC) in Table 1

  • Extensive bowel wall injury and a narrowed intestinal lumen.

  • Complications.

    • May involve intestinal tract or organs unrelated to it.

      • Surgery may be required for small bowel stricture with subsequent obstruction.

      • Fistula formation common.

    • Systemic.

      • Arthritis.

      • Iritis, uveitis, episcleritis, conjunctivitis.

      • Skin and mucosal lesions.

      • Liver disease.

      • Gallstones.

      • Venous thromboembolism

    • Nutritional deficiencies.

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Table Graphic Jump Location
TABLE 1.Comparison of Clinical and Pathologic Features of Crohn’s Disease and Ulcerative Colitis
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EPIDEMIOLOGY

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  • Bimodal age distribution.

    • Peak incidence in second or third decades with second peak between 60 and 80 years of age.

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RISK FACTORS

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  • Smoking associated with increased frequency of CD

  • NSAIDs may trigger disease occurrence or flares.

    • Use may be warranted in patients with arthritis symptoms if benefits outweigh risks.

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CLINICAL PRESENTATION

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  • Highly variable.

    • Single episode may not ...

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