What can cause a sudden change in hemoglobin levels in a 65 yr old man. He is pale, no energy and has lost 10 pounds in 2 weeks. His level went from 15 to an 8. He also has had no injury that caused blood loss. He is set for a colonoscopy and a GI study Tuesday. There has been no blood in his stool and had a normal colonoscopy 10 years ago and also has had no stomach problems. I have ideas but looking for input.
Hello and thanks for the query, It is possible that somewhere in the gastrointestinal tract that he is having a slow and gradual loss of blood.  This can come from ulcers, diverticula, inflamed blood vessels, or possibly from a cancer.  This is why the endoscopy is indicated. If the endoscopy is normal - a workup for hemolysis is indicated - this is where the body is somehow breaking down blood cells causing a Chat Doctor.  This can sometimes be an autoimmune process. Lastly, if all else appears normal an examination of the bone marrow may be indicated.  This would require a referral to a hematologist.  For now - proceed with the endoscopy and then the doctors can determine the next logical step in helping to improve the hemoglobin. One other thing - diet - can affect hemoglobin. In cases of low iron the hemoglobin will be low.  All of this can be assessed with simple blood tests at the discretion of your doctor. Sincerely,