Iron has been low for months, don't eat enough of it, doc wants colon& upper gi done. have no bleeding , 7neg stool cards, why even do those tests?

Iron def. anemia: Blood loss from the digestive tract is a common reason for iron deficiency anemia. Since blood loss from the digestive tract can be an intermittent recurrence, having negative stool cards does not rule out a source of blood loss from the digestive tract. Procedures to look at those portions of the digestive tract are often the only way to know with any certainty if the digestive tract is involved.

Absorption: Sounds like your GI tract is not absorbing iron and that is why your doctor wants further testing. Low iron can be a result of blood loss, which you do not have, or improper absorption. A problem with absorbing iron can be diagnosed sometimes with blood testing but often times requires endoscopy. Ask your doctor if celiac disease is a possibility.