'Sports anemia'--a real or apparent phenomenon in endurance-trained athletes?

In order to critically define the apparently widespread condition 'sports anemia', the red cell indices and iron status of male distance runners and triathletes, and female distance runners and ballet dancers were compared to non-exercising controls of both sexes. The mean hemoglobin (Hb) levels of all groups were within the normal ranges and there was no difference between the athletic and control groups of each sex. The mean serum ferritin (SF) concentration of the male distance runners (79.8 micrograms/l) was significantly lower than that of the triathletes (123.5 micrograms/l) and controls (138.3 micrograms/l). Iron deficiency (SF less than 12 micrograms/l, % saturation less than 18%) was evident in 3.3% and 5% of the male and female runners respectively, and 3.3% of the ballet dancers. Iron deficiency anemia (abnormal red cell indices and iron status) occurred in only 1.7% and 3.3% of the male and female distance runners respectively, and 3.3% of the dancers. However, 7 (11.7%) each of the male and female distance runners and 6 (20.0%) of the ballet dancers recorded hemoglobin values lower than the normal range of 140 g/l and 120 g/l for males and females respectively. This anomaly can be explained by a significantly expanded plasma volume in endurance-trained individuals, causing a 'pseudoanemia'. We conclude therefore that athletes are at no greater risk for developing a frank anemia than the non-exercising population, and that the term 'sports anemia' is misleading, as it does not describe a specific clinical entity.