[The effect of hemodialysis and continuous ambulatory peritoneal dialysis on renal anemia]

Anaemia is an almost invariable sign of chronic renal failure [1]. Although many factors have been implicated as causes of this anaemia, it seems probable that deficiency of erythropoietin is the main cause for most patients [2]. Institution of chronic dialysis can improve anaemia in end-stage kidney disease, continuous ambulatory peritoneal dialysis being reported as more successful [3]. The aim of this study was to investigate the influence of haemodialysis and continuous ambulatory peritoneal dialysis on anaemia during the first six months of treatment. We examined 21 persons (14 males and 7 females, aged from 18 to 78 years) on haemodialysis treatment and 13 persons (6 males and 7 females aged from 22 to 64 years) on continuous ambulatory peritoneal dialysis (Table 1). Standard procedures were used for measuring biochemical parameters. Urea and creatinine levels were high, almost incompatible with life, in all tested persons before dialysis treatment. During the first three months of both dialysis techniques urea and creatinine were significantly (p < 0.01) corrected, but remained above the normal ranges (Table 2). Patients on continuous ambulatory peritoneal dialysis have shown significantly (p < 0.01) lower urea and creatinine values compared to patients on haemodialysis (Graph 1). These data suggest better preservation of renal function and better control of the internal environment during continuous ambulatory peritoneal dialysis [6]. All tested patients were severely anaemic before the beginning of dialysis. During the first six months of haemodialysis erythrocyte count, haematocrit and haemoglobin levels were unchanged (Table 3). Transfusions and hepatitis episodes only temporary improved anaemia. Patients on continuous ambulatory peritoneal dialysis exhibited significant correction of anaemia already during the first three months of treatment (Graph 2). Though less significantly, haemoglobin values continued to rise even during the next three months. The reached haemoglobin levels were lower than normal, but significantly higher than values in patients on haemodialysis (p < 0.01), suggesting better control of anaemia during continuous ambulatory peritoneal dialysis. Transfusion requirement was irrelevant, and hepatitis was not noticed, so they cannot be held responsible for the improvement of anaemia. Greater iron consumption, illustrated by higher transferrin saturation, also confirmed increased erythopoitesis in patients undergoing continuous ambulatory peritoneal dialysis. They also had lower blood iron level than those on haemodialysis (who had) numerous blood transfusions. The improvement of anaemia during continuous ambulatory peritoneal dialysis may be the result of reduction in plasma volume [7] as well as an increase in red cell mass and a better clearance of middle molecules in comparison to patients on haemodialysis. The main cause is higher erythropoietin level [8]. All tested patients had low folic acid level. Patients who corrected anaemia showed fall in folat level. This was statistically remarkable during the first three months of continuous ambulatory peritoneal dialysis-from 3.64 ng/ml to 2.09 ng/ml. All these data suggest that both dialysis modalities are effective in the control of protein waste products level, but continuous ambulatory peritoneal dialysis has better influence on the improvement of anaemia that haemodialysis. This can be attributed to better removal of uremic toxins, improved protein metabolism, lower parathyroid hormone level and higher erythropoietin value due to peritoneal macrophage production.