Crohn Disease
BASICS
DESCRIPTION
- A chronic, progressive inflammatory GI tract disorder, most commonly involving the terminal ileum (80%)
- Hallmark features of Crohn Disease (CD):
- Transmural inflammation that can result in fibrotic strictures, fistulas, fissures, or abscesses; noncaseating granulomas (30%); skip lesions: diseased mucosa interspersed with normal mucosa; can be continuous, mimicking ulcerative colitis (UC); rectal sparing; diverse presentations: ileitis (1/3), ileocolitis (1/3); isolated colitis (1/3)
EPIDEMIOLOGY
Incidence
3 to 20 cases per 100,000 person-years in North America; incidence is rising globally. Women are slightly more affected than men; increased incidence in northern climates
Prevalence
247 cases per 100,000 persons
ETIOLOGY AND PATHOPHYSIOLOGY
- Genetics, environmental triggers, commensal microbial antigens, and immunologic abnormalities result in activation of inflammatory cells and subsequent tissue injury.
Genetics
- 15% of CD patients have a first-degree relative with inflammatory bowel disease (IBD); first-degree relative of an IBD patient has 3- to 30-fold increased risk of developing IBD by age 28 years.
- Associated genetic syndromes: Turner and Hermansky-Pudlak syndromes, glycogen storage disease type 1b
RISK FACTORS
Environmental factors:
- Cigarette smoking doubles the risk of CD; tobacco cessation reduces flares and relapses.
- Dietary factors: higher incidence if diet high in refined sugars, animal fat or protein, processed or ultraprocessed foods
COMMONLY ASSOCIATED CONDITIONS
- Extraintestinal manifestations
- Arthritis (20%): seronegative, small and large joints (ankylosing spondylitis [AS] or sacroiliitis [SI], associated with HLA-B27); skin disorders (10%): erythema nodosum, pyoderma gangrenosum, psoriasis; ocular disease (5%): uveitis (associated with HLA-B27), iritis, episcleritis
- Kidney stones: calcium oxalate stones (from steatorrhea and diarrhea) or uric acid stones (from dehydration and metabolic acidosis); osteopenia and osteoporosis; hypocalcemia; hypercoagulability: venous thromboembolism prophylaxis essential in hospitalized patients; gallstones: cholesterol stones resulting from impaired bile acid reabsorption; primary sclerosing cholangitis (PSC) (5%)
- Conditions that parallel disease activity
- Peripheral arthropathy (not SI and AS); episcleritis (not uveitis); oral aphthous ulcers and erythema nodosum
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Citation
Domino, Frank J., et al., editors. "Crohn Disease." 5-Minute Clinical Consult, 34th ed., Wolters Kluwer, 2026. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688851/0.4/Crohn_Disease.
Crohn Disease. In: Domino FJF, Baldor RAR, Golding JJ, et al, eds. 5-Minute Clinical Consult. Wolters Kluwer; 2026. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688851/0.4/Crohn_Disease. Accessed July 16, 2025.
Crohn Disease. (2026). In Domino, F. J., Baldor, R. A., Golding, J., & Stephens, M. B. (Eds.), 5-Minute Clinical Consult (34th ed.). Wolters Kluwer. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688851/0.4/Crohn_Disease
Crohn Disease [Internet]. In: Domino FJF, Baldor RAR, Golding JJ, Stephens MBM, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2026. [cited 2025 July 16]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688851/0.4/Crohn_Disease.
* Article titles in AMA citation format should be in sentence-case
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T1 - Crohn Disease
ID - 1688851
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ED - Baldor,Robert A,
ED - Golding,Jeremy,
ED - Stephens,Mark B,
BT - 5-Minute Clinical Consult, Updating
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PB - Wolters Kluwer
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DB - Medicine Central
DP - Unbound Medicine
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