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Case study (25) – Crohn's disease caused Megaloblastic anemia

Case study (25) – Crohn's disease caused Megaloblastic anemia

Case study (25) – Crohn's disease caused Megaloblastic anemia


A 42-year-old woman with a 2–to 3-month history of abdominal pain, diarrhea, and rectal bleeding. 

She passes blood-stained motions four to six times each day. 

She also gradually felt tired and lost appetite. 

On examination she is pale. There is no lymphadenopathy. 

She has mild generalized abdominal tenderness, but there is no organomegaly. 

Laboratory Investigation: 

1. CBC: 

Hemoglobin (Hb) 84 g/L 

Mean corpuscular volume (MCV) 110 fL 

White blood cells (WBC) 3.1  109/L 

Platelets 80 109/L 

2. Other Investigations:

- Biochemistry is normal. 

- Erythrocyte sedimentation rate (ESR) 86 mm/h. 


Q1: What diagnosis is suggested by the barium meal and follow-through?

Q2: What abnormalities are seen in her bone marrow aspirate?

What is the diagnosis? 

Q3: What further investigations would you perform? 


A1: The barium meal and follow-through show classical changes of Crohn’s disease. 

There is evidence of mucosal thickening and edema with flocculation of barium. 

A2: The bone marrow appearances are those of megaloblastic anemia. 

The nucleated red cells show an open nuclear chromatin pattern (most clearly seen on the high-power view of erythroblasts). 

There are giant metamyelocytes in the white cell series. 

A3: Important additional investigations include assessment of hematinic – iron studies, serum ferritin, serum B12, and serum and red cell folate levels. 

Crohn's disease is the most likely cause of megaloblastic anemia due to malabsorption of vitamin B12 caused by disease of the terminal ileum. 

Vitamin B12 absorption studies are no longer performed. 

A radioactive carbon breath test would be a helpful further investigation, as it would exclude the presence of an intestinal stagnant loop with bacterial overgrowth.