A physician questions the results of a urinalysis which was reported to show a negative nitrite, yet contained 2 bacteria. Suggest a course of action and explanation why these findings are consistent

The physician asks the patient about her diet after reviewing these results. The patient reveals a healthy diet, but reminds the physician that she had a gastric bypass 6 years ago. Therefore, she does not eat large quantities of food at any one time. The procedure was done in another state, as the patient recently moved to the area, and this information was not on the patient’s chart. The physician decides to order iron studies to investigate the cause of the anemia. Iron levels are low. Ferritin levels are low. TIBC levels are high. With this added health history and iron study results, it is confirmed that the patient’s anemia is caused by what?