{"id":10682,"date":"2025-11-10T06:02:03","date_gmt":"2025-11-10T06:02:03","guid":{"rendered":"https:\/\/www.kauveryhospital.com\/ima-journal\/?p=10682"},"modified":"2025-11-10T06:03:00","modified_gmt":"2025-11-10T06:03:00","slug":"a-hematologic-window-to-an-intestinal-disease-crohns-disease-presenting-as-b12-deficiency","status":"publish","type":"post","link":"https:\/\/www.kauveryhospital.com\/ima-journal\/ima-journal-november-2025\/a-hematologic-window-to-an-intestinal-disease-crohns-disease-presenting-as-b12-deficiency\/","title":{"rendered":"A Hematologic Window to an Intestinal Disease: Crohn\u2019s Disease Presenting as B12 Deficiency"},"content":{"rendered":"

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Case Presentation<\/h2>\n

A 32-year-old male presented with constipation, painful defecation, and streaks of blood in stools on and off. He also complained of abdominal discomfort, generalized weakness, and easy fatiguability for three months, along with loss of appetite and weight. There was no history of diarrhea, fever, or drug intake.<\/p>\n

On examination, he was conscious and oriented with stable vitals. Pallor and mild icterus were present. Abdominal examination revealed mild tenderness in the left iliac fossa without organomegaly.<\/p>\n

Initial blood investigations were consistent with Pancytopenia (Hb 6.9 g\/dL, MCV 112 fL). Peripheral smear showed macrocytosis, ovalocytes, target cells, and hypersegmented neutrophils, suggestive of megaloblastic anemia. Biochemistry revealed mild indirect hyperbilirubinemia and mildly elevated transaminases. Serum vitamin B12 was 83 pg\/mL and folate 1.2 ng\/mL. Intrinsic factor and parietal cell antibodies were negative, ruling out pernicious anemia. Fecal Calprotectin was elevated.<\/p>\n

CT Enterography<\/strong> showed diffuse smooth mucosal enhancement of small and large bowel loops, pulled up caecum and suspicious inflammatory changes in ileocaecal junction.<\/p>\n

Upper GI endoscopy<\/strong> revealed erosive bulbar duodenitis and erosive gastritis, while colonoscopy <\/strong>demonstrated ulcerative(<15mm) terminal ileitis and pancolitis with scattered aphthoid ulcers (<3 mm) along the colon.<\/p>\n

Histopathology<\/strong> from terminal ileum showed patchy severe active ileitis with ulceration and reactive lymphoid hyperplasia, while colonic biopsies<\/strong> showed focal mild active colitis, both negative for granulomas, dysplasia, and malignancy. Jejunal biopsy<\/strong> showed mild active jejunitis, and gastric biopsy<\/strong> revealed chronic active gastritis with mild atrophy, H. pylori negative. GeneXpert for tuberculosis and ASCA (IgA) were negative.<\/p>\n

A Diagnosis <\/strong>of Crohn\u2019s disease involving the terminal ileum and colon, presenting as vitamin B12 deficiency anemia with pancytopenia, was made.<\/p>\n

The patient was managed with parenteral vitamin B12 injections, folic acid, PPIs, and supportive therapy, along with aminosalicylates and systemic corticosteroids after confirmation of inflammatory bowel disease. He showed significant symptomatic and hematologic improvement and was discharged in a stable condition with advice for gastroenterology follow-up.<\/p>\n

Discussion<\/h2>\n

Crohn\u2019s disease (CD) is a chronic idiopathic inflammatory bowel disease (IBD) characterized by transmural granulomatous inflammation that can involve any segment of the gastrointestinal tract \u2014 most frequently the terminal ileum. The disease typically presents with chronic diarrhea, abdominal pain, and weight loss. However, in a subset of patients, extraintestinal or atypical presentations may precede classic symptoms.<\/p>\n

In the present case, the index manifestation was severe macrocytic anemia with bicytopenia, with few gastrointestinal complaints. This atypical presentation delayed the suspicion of IBD until endoscopic evaluation and histopathology confirmed ileocolonic Crohn\u2019s disease.<\/p>\n

Mechanisms Linking Crohn\u2019s Disease and Vitamin B12 Deficiency<\/h2>\n

Vitamin B12 absorption occurs in the terminal ileum through an intrinsic factor\u2013dependent mechanism. Involvement of this segment in Crohn\u2019s disease leads to:<\/p>\n