Running low on iron?

Well, this is puzzling. Some weeks ago, at the beginning of a blood donation process, where they take some blood from one's finger to do the hemoglobin test, my results were just shy of the minimum level. I was disappointed to have to defer my donation--for the first time in decades of donations. 2-3 months prior, I had my annual physical just a few days after my previous blood donation, and one of the lab results indicated a possible anemia condition. My internist thought there might be a connection between the two.

Just out of curiosity, to see if anemia might be related in any way to running, I googled running and anemia, and, sure enough, there were gobs of related articles out there, including a number of academic peer-reviewed papers. From the few I have read so far, there seems to be agreement that iron deficiency and anemia are more common among endurance athletes than among the general population, and, of the endurance athletes, more common among runners. Various explanations for the higher rates among runners include iron loss through sweating, normal gastrointestinal bleeding during long runs, destruction of red blood cells from all that pounding on pavement ("footstrike hemolysis"), and iron depletion associated with tissue inflammation. The connection between endurance training and iron deficiency anemia, however, remains to be firmly established. As one author questioned, does it make sense that intense exercise, as a normal outcome, reduces the body's capacity to perform intense exercise (by accelerating iron depletion resulting in anemia). Adding to the confusion, there is also the so-called "pseudoanemia," indicated by a low hematocrit value (ratio of red cell volume to total blood volume), which manifests itself in a well-conditioned body due to an expansion of blood volume.

In a recent follow-up lab test, the new results showed the relevant numbers being higher but still lower than normal. My doctor said his money is on blood donation as the likely cause. Me? I am on the fence for now, though leaning towards running as the cause. Although donating blood as the cause of anemia does make sense, it has been several months now since my last donation, and I have no symptoms of anemia. Certainly not fatigue. I am in my last week of training for next weekend's Baltimore Marathon and had a great long run last weekend (last one before the race). Although I have been running all my life, I have not, for the most part, run at the volume that I have sustained since I began training for the 2011 Marine Corps Marathon around June of last year. I have started to take an iron supplement, but I plan to have another conversation with my doctor in a few months to see if the supplement is really needed.