Is fatigue dependent on anemia?
MARCELLA PALAD, MD, of Orangeville, ON, wonders, "Not infrequently, and perhaps inappropriately, I check ferritin levels in patients complaining of fatigue. The ferritin level returns in the low range (< 20 Âµg/L) with a normal hemoglobin. Do we treat these people with iron, and to what extent should ferritin be targeted? Is fatigue dependent on a diagnosis of anemia?"
There are numerous reasons for tiredness. Iron deficiency, without anemia, may cause fatigue. On the other hand, both the fatigue and iron deficiency may be due to some underlying condition. Or the tiredness may be unrelated to iron. There's nothing wrong in giving the patient a trial of iron therapy to see if the fatigue disappears or not, as long as you also make every effort to find out the cause of the low serum ferritin, regardless of the results of the trial. Individuals with low serum ferritin should be investigated in the same way as if they had iron deficiency anemia, even if the hemoglobin and red cell indices are normal. Scurvy and hypothyroidism may also be associated with low serum ferritin, but these are much less common and you still need to make sure that the patient isn't having chronic blood loss. The tiredness associated with iron deficiency disappears very fast (in a few days) long before the improvement of anemia. The duration of ferritin therapy depends on the cause of the iron deficiency. AS