TREATMENT OF ANEMIA IN HEMODIALYSIS-PATIENTS WITH ERYTHROPOIETIN - LONG-TERM EFFECTS ON EXERCISE CAPACITY

1. The effects of correcting anaemia on exercise capacity were evaluated in 21 haemodialysis patients (aged 39 +/- 12 years) before starting treatment with recombinant human erythropoietin (Hb concentration, 73 +/- 10 g/l; total Hb, 59 +/- 12% of expected), after correction of the anaemia to a Hb concentration of 108 +/- 7 g/l and a total Hb 82 +/- 10% of expected, and in 13 of the patients after 12 months on maintenance recombinant human erythropoietin treatment (Hb concentration 104 +/- 14 g/l, total Hb 79 +/- 17% of expected). Fifteen healthy subjects (aged 41 +/- 9 years), who took no regular exercise, constituted the control group. Maximal exercise capacity was determined on a bicycle ergometer. Oxygen uptake, respiratory quotient, blood lactate concentration, heart rate and blood pressure were measured at rest and at maximal workload. 2. After 6 +/- 3 months on recombinant human erythropoietin, maximal exercise capacity increased from 108 +/- 27 W to 130 +/- 36 W (P<0.001) and the maximal oxygen uptake increased from 1.24 +/- 0.39 litres/min to 1.50 +/- 0.45 litres/min (P<0.001). No significant changes in respiratory quotient (1.16 +/- 0.13 versus 1.18 +/- 0.13) and blood lactate concentration (4.0 +/- 1.8 versus 3.6 +/- 1.1 mmol/1) at maximal workload were observed, but the blood lactate concentration in the patients was significantly lower than that in the control subjects (6.7 +/- 2.3 mmol/l, P<0.01). After the correction of anaemia, the aerobic power was still 38% lower in the patients than in the control subjects and 17% lower than the reference values. 3. After 12 months on maintenance recombinant human erythropoietin treatment (17 +/- 3 months from the start of the study), no further significant changes were observed in maximal exercise capacity (before start, 112 +/- 31 W, 6 +/- 3 months, 134 +/- 42 W, 17 +/- 3 months, 134 +/- 50 W), maximal oxygen uptake (before start, 1.33 +/- 0.45 litres/min; 6 +/- 3 months, 1.59 +/- 0.54 litres/min; 17 +/- 3 months, 1.75 +/- 0.78 litres/min) or blood lactate concentration (before start, 4.4 +/- 1.9 mmol/l; 6 +/- 3 months, 4.0 +/- 1.0 mmol/l; 17 +/- 3 months, 4.7 +/- 2.0 mmol/l). 4. Thus, in haemodialysis patients the improvement in maximal aerobic power after the correction of anaemia persists without marked changes during long-term treatment with recombinant human erythropoietin. We did not observe any effects on exercise capacity that could be attributed to a spontaneous increase in physical activity after treatment of anaemia.