My 81 year old father was admitted to the hospital when his hemoglobin dropped to 6.5.  His hemoglobin was 10 back in November but no one was concerned.  He has not had any obvious blood loss and his rectal exam was clear.  He is in advanced stages of Alzheimers and was diagnosed with Pancreatic Cancer 7 years ago which has been controlled with the radioative pellets.  He received two units of blood which quickley pinked up his skin and gave him more energy.  The ER suggested we go to a Hemotologist/Oncologist where they took 10 viles of blood and we are awaiting the results.
Hi, Hemoglobin in the elderly is multifactorial. Possible cause with no obvious blood loos and rectal exam being clear points towards malnutrition. As he is in advanced stage of Alzheimer's, his diet might be irregular. Also, due to malabsorption secondary to atrophic changes secondary to old age, essential nutrients might not be getting absorbed. He would require injectable iron, it b12 and folic acid supplements to improve the hemoglobin. Also try to improve his nutrition in diet. Besides, Packed red cell transfusion could be necessary in hemoglobin Chat Doctor. Any further queries, happy to help again.