Sorry, this post is a little more technical than most, but I thought it was interesting enough to share...
I saw a patient today who had chronic normocytic anemia. The patient was an older man, so the most likely cause of his anemia was chronic bleeding.
The patient has had bladder surgery in the past and had high creatinine values recently, so his doctor's initial impression was that the bleeding was likely from the urinary tract, which is a very reasonable theory.
Urine tests found some microalbuminuria, but no hematuria (blood in the urine) or proteinuria. Basically, his urinary system had nothing to do with his anemia.
Initial test results showed that he was iron deficient, but his anemia was normocytic, not microcytic, so a CBC looking at B12 and folate was ordered. His folate was normal, but his B12 was low. Iron and B12 deficiencies explain why the anemia was normocytic, but why was he B12 deficient? He was not an alcoholic, nor was he malnourished...he should be getting enough B12.
My running theory is that the chronic bleeding is coming from the GI tract, specifically, the stomach. He has peptic ulcers that interfere with his production of intrinsic factor and prevent him from absorbing B12 from his diet. These ulcers are also bleeding, causing his anemia.