If I am anemic, does it mean that I have cancer?

I am interested in finding out information on anemia. I am 49, and I was given a blood test during my menstrual cyle. I have been asked to see a gastroenterologist for a test for colon cancer, ulcers etc. Why not let me take iron pills and then be reevaulated?

This letter raises some interesting issues, and certainly many doctors will react in many different ways to the question being posed. I will try to give my thoughts and approach.

All doctors trained in this country have drilled into them, from their first day in medical school, the importance of investigating people who have iron-deficiency anemia to determine if the iron deficiency is being caused by a hidden cancer. Iron deficiency is a fairly early sign of cancers or ulcers in the gastrointestinal tract, and since colon cancer remains a major killer in our society, the importance of catching it early is always emphasized.

Doc’s Advice 300x279 If I am anemic, does it mean that I have cancer?

Doc’s Advice: If I am anemic, does it mean that I have cancer?

So the answer to the problem is easy, you may say: Everyone with iron-deficiency anemia should be checked out for cancer. But it’s much more complicated than that. Iron-deficiency anemia is predominantly a disease of young women, who lose iron every month in their menstrual periods, while colon cancer is largely a disease of the elderly, and affects men as often as women. If we do colonoscopies on everyone with iron-deficiency anemia, we will be doing literally millions of these expensive and potentially harmful procedures, and finding very few cancers.

We can agree that iron deficiency in men and all older people should be investigated, but our letter is from a 49-year-old woman who is still menstruating. What about her? Before trying to answer that, I want to introduce two other complications (of many). One is that some labs are not as careful in calibrating their instruments as others, and therefore find mild cases of anemia in people who really are not anemic. What can a doctor do about that? Never trust a single test! Repeat it, and if possible repeat it with another test that will confirm your worry about iron deficiency. Before I refer a patient for an extensive workup, I always reconfirm the test, and do a ferritin test, which is useful to evaluate the total amount of iron in the body. If it is low, the iron deficiency is confirmed. If it is not low, then either the lab was originally in error, or the person has already been taking iron pills on their own, or the person has one of the common anemias which looks like iron deficiency but really is not, such as thalassemia trait.

If she has already been taking iron pills when the ferritin test is done, then it doesn’t clear her, since there will be a lag between the time that the ferritin goes up and the time that the blood count goes back to normal. Consequently, taking iron pills and not informing the doctor will complicate the evaluation, and may mask an anemia that really is from a colon cancer.

So let’s say that today’s writer has a ferritin test done, and it is low. But she says, “I have always had heavy periods, and I still have them, and every time I have had my blood checked since adolescence I have been anemic.” She may indeed be right. Lots of women do go through their entire adult lives mildly anemic because of heavy periods. In this case her doctor might then say, “Well let’s check your stools to see if you are loosing blood from that source. If you are, then it’s not simply your periods, and you must have the workup.” And I would agree. But if many, repeated, careful stool tests show no blood, he or she might say “Let’s wait, take iron, and recheck the stools in three months.” After the iron, checking the stools for blood will be the only useful test, since the blood count and ferritin should go back to normal.

In someone with a family history of colon, breast, or ovarian cancers I would be more insistent on doing the colonoscopy now, since there are several different kinds of familial colon cancers. After ages 60-65, people who are going to get familial colon cancer have gotten it, and the rest of us have the ordinary risk for the disease. Since our writer is 49, if she has any close family members with those cancers, I would be more aggressive. Because all these many issues can be fully evaluated only by a person in consultation with her doctor, whether she does or does not go for further testing at this time must be their decision.

Today’s writer mentioned having the blood test when she was menstruating. This does not change the picture. If she has iron-deficiency anemia, it will not matter whether she is menstruating when the test is done or not, and if she is not iron-deficient, with a normal ferritin, then the issue of menstruation is irrelevant.

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