Crohn's disease is a chronic inflammatory bowel disease (IBD) in which inflammation can affect any part of the digestive tract — from mouth to anus — but most often the end of the small intestine and the beginning of the large intestine.
One of the most common extraintestinal complications of Crohn's disease is anemia, and it often has a mixed nature.
What Crohn's disease is
Inflammation in Crohn's disease involves the full thickness of the bowel wall and occurs in 'patches'. Manifestations: diarrhea, abdominal pain and cramps, weight loss, fatigue, fever; joints, eyes and skin can also be affected. The course is wave-like — flares alternate with remissions. A related disease is ulcerative colitis, but it affects only the large intestine.
Why anemia develops
Anemia in Crohn's disease is usually mixed. First, it is iron deficiency — from chronic blood loss from the inflamed lining and impaired absorption. Second, it is anemia of chronic inflammation: active inflammation raises hepcidin, and iron becomes unavailable for blood cell production. When the end of the small intestine is affected, vitamin B12 absorption is additionally impaired.
Diagnosis and treatment
The diagnosis is made from a combination of data: complaints, blood and stool tests (including inflammation markers), colonoscopy with biopsy, and imaging if needed. Treatment aims to suppress inflammation (anti-inflammatory and immunosuppressive drugs, biologic therapy), and anemia is corrected with iron supplements — often intravenous during active inflammation, since absorption from tablets is reduced.
Calculate using this marker
Calculators where Crohn's disease is used directly:
Frequently asked questions
Why does iron in tablets help poorly in Crohn's disease?
During active inflammation, hepcidin is elevated and blocks iron absorption in the gut. That is why intravenous iron is often more effective in a flare than oral supplements.
How is Crohn's disease different from ulcerative colitis?
Crohn's disease can affect any part of the GI tract and involves the full thickness of the wall in patches; ulcerative colitis is limited to the large intestine and its surface layer. Both belong to the inflammatory bowel diseases.