Increased red cell 2,3-diphosphoglycerate levels in haemodialysis patients treated with erythropoietin.

The efficacy of recombinant human erythropoietin (rHuEpo) for the treatment of renal anaemia is well established. To assess the effect of rHuEpo treatment on physical performance we evaluated physical working capacity, oxygen uptake and red cell 2,3-diphosphoglycerate (DPG) values at rest and during and after exercise on a bicycle spiroergometer in eight chronically haemodialysed patients. Follow-up examination was carried out after a mean of 14 weeks (range 9-19 weeks), when mean haemoglobin had increased from 7.8 to a stable value of 13.0 g/dl in response to rHuEpo treatment (P < 0.001). Physical working capacity and oxygen uptake at the anaerobic threshold (4 mmol/l blood lactate concentration) increased from 68 +/- 12 to 80 +/- 16 watts and 0.95 +/- 0.14 to 1.10 +/- 0.20 l/min, respectively (P < 0.01). DPG, which determines oxygen affinity to haemoglobin in red cells, increased by 13% from 13.7 +/- 1.5 to 15.5 +/- 2.2 mumol/g Hb (P < 0.05). With maximal exercise mean DPG values significantly decreased to a much lower level without rHuEpo treatment than after correction of anaemia. Therefore rHuEpo treatment results both in better oxygen transport capacity and reduced intraerythrocytic oxygen affinity, which is followed by improved oxygen delivery to tissues per unit of haemoglobin. These effects may explain the improvement of exercise capacity observed in dialysis patients after rHuEpo treatment.