Dear Dr. Roach: I’m a 73-year-old male. My recent bloodwork showed a mild anemia. My doctor ordered a second blood test and a cancer screening kit. The anemia was stable, and the screening was normal with no microscopic blood detected. He is not sure why my bloodwork showed a mild anemia and has me scheduled to repeat testing every three months. He has requested that I monitor my stools for evidence of bloody or black diarrhea.
There has been no evidence of such as of yet. I had a colonoscopy a little over three years ago that resulted in one polyp being removed, and I had mild inflammation in my colon that was attributed to the solution used to clean out the colon.
Is there any possible explanation for the mild anemia other than looking for evidence of blood in my stools?
In other words, is bleeding in the intestinal tract the only explanation for my mild anemia?
My doctor is reluctant to order a colonoscopy unless there is evidence of bleeding, since it has only been three years from my last one.
Anemia, Latin for “too little blood,” just means the blood count is lower than normal for a person’s age and condition. In general, there are two major categories of anemia: your body is not making enough, or you’re losing blood. However, both can exist at the same time.
If you’re not making enough blood, it can be because of a lack of the nutrients needed to do so. Folic acid, vitamin B-12 and iron are the most common nutrients to cause this. Your doctor normally would check this once the anemia is confirmed. If it’s the case, treatment is both replacing the nutrient and figuring out why you didn’t have enough to begin with. Diet alone is a rare cause. Diseases of the bone marrow, of which there are many, is the other major class of underproduction anemias. At age 73, your doctor should be considering that possibility, which often requires a visit to a hematologist and a biopsy of the bone marrow to sort out for certain.
Losing blood is sometimes obvious, but when it isn’t, the gastrointestinal tract is, by far, the leading place it is lost. Colon cancer is the first concern, but that is unlikely (but not impossible) only three years out from a normal colonoscopy. Still, it is drilled into us in medicine that iron deficiency in a man or a post-menopausal woman is presumed to be colon cancer until you prove it isn’t. A colonoscopy three years ago might not be strong enough evidence that there is no source of blood loss in the colon; it could develop in three years, and even the best colonoscopy can occasionally miss small lesions.
I suspect you might be iron deficient, which is why your doctor is so concerned about loss from your gut. There are cases where the iron deficiency is from another cause besides bleeding (poor absorption due to celiac disease is a common one), and this can lead to confusion.
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