Hello, Thanks for the query. I have gone through your short description and I can understand your concerns. There are many conditions which causes minor bleeding in your gut(gastrointestinal tract) with out causing any clinical symptoms. These are incidental findings detected in routine checkups. You may not have any clinical symptoms apart from fatigue and general weakness. I will explain the probable causes for undetected GI bleed. (1)-Peptic ulcer disease: You may have small ulcers over your stomach or small intestine which bleeds very slowly. You don t even have pain. (2)-Hemorrhoids: Hemorrhoids or piles are the common cause for undetected GI bleed especially in elderly. (3)-Alcoholic liver disease:- Liver damage caused by excessive alcohol intake can cause cirrhosis and anemia. (4)-Crohn s disease:- This rare autoimmune disease can also cause internal bleeding and anemia. (5)-Colorectal Cancer and stomach cancer:- These can also rarely cause similar clinical picture. You have to do a colonoscopy and OGDscopy to find out the exact bleeding spot. Additional investigations like CT and MRI may be needed based on evaluation. As of now blood transfusion may be needed to correct iron deficit. Hope I have answered your query Regards. Dr.Shinas Hussain