The effect of erythropoietin on lactate, pyruvate and excess lactate under physical exercise in dialysis patients.

To investigate EPO-induced increase of hemoglobin on energy metabolism plasma concentrations of lactate (L), pyruvate (P) and excess lactate (XL) were determined in ten dialysis patients at rest, immediately after 6 minutes of ergometric exercise as well as after recovery for 15 and 30 min. The investigations were performed before EPO-therapy at a mean Hb = 7.5 +/- 0.9 g/dl and under EPO-therapy at a mean Hb = 10.0 +/- 0.6 g/dl and at a mean Hb = 11.9 +/- 0.8 g/dl. Ten healthy subjects were subjected to the same investigation at Hb = 14.7 +/- 1.1 g/dl. There was a significant rise of L and XL in all patient groups under ergometric exercise. The increase of hemoglobin from 7.5 g/dl to 10.0 g/dl led to significantly (p < 0.01) lower L and XL concentrations immediately after exercise (L = 4.62 vs 3.23 mmol/l, XL = 2.37 vs 1.38 mmol/l). The further decrease of the mean L and XL values (L = 2.88 mmol/l, XL = 1.05 mmol/l) associated with the rise of hemoglobin to 11.9 g/dl could not be confirmed statistically. In contrast to all patient groups, there was no significant rise in XL in the healthy control subjects under physical exercise. The present results make it evident that patients with renal anemia react even to light physical exercise with pronounced tissue hypoxia in contrast to healthy subjects. The increase of the hemoglobin content under the EPO-therapy leads to a marked reduction of the tissue hypoxia and consequently of anaerobic energy production. A further rise of the hemoglobin content above and beyond 10.5 g/dl will have an additional positive effect on oxygen supply only in occasional cases. The comparison with healthy subjects shows that despite a very large degree of normalization of the hemoglobin content, no normalization of energy metabolism can be attained.