my dad is 81, his hemoglobin has gone from 13.8 to 9.4 over the course of 1 year, he has dementia but otherwise happy, comfortable and safe. i don t think i want to put him through a colonoscopy. what can i do next to determine cause of anemia? we ve checked CBC, serum iron, ferritin and cea, and he has had ct of chest, abdomin and pelvis.