Crohn's disease

Crohn's disease
Other namesCrohn disease, Crohn syndrome, granulomatous enteritis, regional enteritis, Leśniowski-Crohn disease
Endoscopic image of severe Crohn's colitis showing diffuse loss of mucosal architecture, friability of mucosa in sigmoid colon and exudate on wall.
SpecialtyGastroenterology
SymptomsDiarrhea, abdominal pain, fatigue, weight loss, fever[1]
ComplicationsAnemia, bowel cancer, bowel obstruction, strictures, fistulas, abscesses, anal fissure[1]
Usual onset20–30 years[2]
DurationLifelong[1]
CausesUncertain[1]
Risk factorsGenetic predisposition, living in a developed country, smoking, diet,[1] antibiotics, oral contraceptives, aspirin, NSAIDS[3]
Diagnostic methodColonoscopy, capsule endoscopy, medical imaging, histopathology[1]
Differential diagnosisUlcerative colitis, Behçet's disease, intestinal lymphoma, intestinal tuberculosis, ischaemic colitis, irritable bowel syndrome[1]
MedicationBiologics (especially TNF blockers), immunosuppressants (thiopurines and methotrexate), corticosteroids,[1]
PrognosisSlightly reduced life expectancy[4]
Frequency~300 in 100,000 (North America and Western Europe)[1]
Named after

Crohn's disease is a chronic inflammatory bowel disease characterized by recurrent episodes of intestinal inflammation, primarily manifesting as diarrhea and abdominal pain. Unlike ulcerative colitis, inflammation can occur anywhere in the gastrointestinal tract, though it most frequently affects the ileum and colon, involving all layers of the intestinal wall. Symptoms may be non-specific and progress gradually, often delaying diagnosis. About one-third of patients have colonic disease, another third have ileocolic disease, and the remaining third have isolated ileal disease. Systemic symptoms such as chronic fatigue, weight loss, and low-grade fevers are common. Organs such as the skin and joints can also be affected. Complications can include bowel obstructions, fistulas, nutrition problems, and an increased risk of intestinal cancers.[1]

Crohn's disease is influenced by genetic, environmental, and immunological factors. Smoking is a major modifiable risk factor, especially in Western countries, where it doubles the likelihood of developing the disease. Dietary shifts from high-fiber to processed foods may reduce microbiota diversity and increase risk, while high-fiber diets can offer some protection. Genetic predisposition plays a significant role, with first-degree relatives facing a five-fold increased risk, particularly due to mutations in genes like NOD2 that affect immune response. The condition results from a dysregulated immune response to gut bacteria and increased intestinal permeability, alongside changes in the gut microbiome.[1]

Diagnosing Crohn's disease can be complex due to symptom overlap with other gastrointestinal disorders. It typically involves a combination of clinical history, physical examination, and various diagnostic tests. Key methods include ileocolonoscopy, which identifies the disease in about 90% of cases, and imaging techniques like CT and MRI enterography, which help assess the extent of the disease and its complications. Histological examination of biopsy samples is the most reliable method for confirming diagnosis.[1]

Management of Crohn's disease is individualized, focusing on disease severity and location to achieve mucosal healing and improve long-term outcomes. Treatment may include corticosteroids for quick symptom relief, immunosuppressants for maintaining remission, and biologics like anti-TNF therapies, which are effective for both induction and maintenance. Surgery may be necessary for complications such as blockages. Despite ongoing treatment, Crohn's disease is a chronic condition with no cure, often leading to a higher risk of related health issues and reduced life expectancy.[1]

The disease is most prevalent in North America and Western Europe, particularly among Ashkenazi Jews, with prevalence rates of 322 per 100,000 in Germany, 319 in Canada,[1] and 300 in the United States.[5] There is also a rising prevalence in newly industrialized countries, such as 18.6 per 100,000 in Hong Kong and 3.9 in Taiwan. The typical age of onset is between 20 and 30 years, with an increasing number of cases among children.[1]

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