Evaluation of erythropoietin in endurance runners.

To evaluate the role of erythropoietin (Epo) in the erythroid abnormalities often found in athletes, Epo was evaluated by radioimmunoassay in endurance runners (ER). In a first study, 46 experienced ER, 11 with iron deficiency (ID group), were studied during a training period. In ID and non-ID runners, serum Epo (SEpo) levels were similar to sedentary controls (ID = 19.1 +/- 4.9 U/L, non-ID = 19.7 +/- 5.5 U/L and controls 19.7 +/- 9.2 U/L). In a second study, serum and urine erythropoietin (UEpo) levels were evaluated in 17 ER during a 6-hour race. Samples were taken before the race (pre-race), immediately following (6-hour) and 4 days after (post-race). No differences were observed in SEpo levels (pre-race = 19.8 +/- 4.1 U/L, 6-hour = 21.2 +/- 4.9 U/L and post-race = 21 +/- 4 U/L), but UEpo increased following the race (pre-race = 15.4 +/- 9.6 U/L, 6-hour = 26.1 +/- 6.2 U/L and post-race = 14.1 +/- 6.5 U/L) (p < 0.0001) and this UEpo increase was related to urine creatinine changes (rs = 0.79, p < 0.00001). In conclusion, SEpo in ER does not differ from sedentary values and does not vary with competition; however, UEpo increases during a long-distance race. These data may be important for a correct evaluation of Epo abusers and sports anemia.