Chronic iron def & anemia (5 yrs) . iv iron good for 6 months. no endometriosis, fibroids, colon polyps, etc. wth? (3 endoscopes, 2 colonoscopies)

See below: Other potential sources are small bowel chronic bleeding, which can best be evaluated by capsule endoscopy and bleeding from excessively heavy menses. As part of your work up i assume you have had all the usual blood test for iron levels (ferritin, transferrin, fe sat etc).

May not be colon: You do not mention that you have seen a hematologist. You may need to do that for further workup, if no cause for bleeding is found. Also, there is a way to look at the small bowel to make sure the bleeding is not coming from there, called a capsule endoscopy, where you swallow a capsule with a camera in it. See your gastroenterologist.