Correlation between erythropoietin and lactate in humans during altitude exposure

The plasma concentrations of both immunoreactive erythropoietin (EPO) and l actate were determined in four healthy untrained subjects at sea level and on the 2nd or 3rd day at altitudes (1,300 and 3,500 m), The mean plasma EPO (18.8+/-1.6 mU/ml at sea level) increased significantly on the 3rd day at 1,300 m (25.5+/-2.0 mU/ml, p<0.05) and showed an almost threefold increase on the 2nd day at 3,500m (53.5+/-3.7 mU/ml, p<0.001). Likewise, the mean pl asma lactate at 3,500m (3.98+/-0.27 mmol/l) was 3.6 times as high as that a t sea level (1.11+/-0.05 mmol/l) (p<0.001). The plasma EPO concentrations w ere found to correlate well with the lactate concentrations at sea level an d altitudes (r=0.86, p<0.01). These results are consistent with the well-kn own EPO/lactate response to altitudes and suggest that the circulating EPO concentration as well as blood lactate concentration can be used as an inde x of anaerobic condition.