OXYGEN AND 2,3-BIPHOSPHOGLYCERATE (2,3-BPG) DURING HEMODIALYSIS

Eleven patients with chronic renal failure who were being treated with haemodialysis three times a week were monitored for a total of 34 hae modialysis sessions. Erythrocyte 2,3-biphosphoglycerate (2,3-BPG) conc entration was analysed immediately before initiation of bicarbonate ha emodialysis and 1 h afterwards. The 2,3-BPG concentration was expresse d relative to the haemoglobin tetramer (Hb(4)) concentration as the 2, 3-BPG/Hb(4) ratio and compared with blood gas analyses and biochemical variables important for characterizing uraemia. During the first hour bf haemodialysis the 2,3-BPG/Hb(4) ratio decreased (p < 0.002), but t he magnitude of the decrease did not significantly correlate with the 2,3-BPG/Hb(4) ratio measured before haemodialysis (p = 0.104). The dec rease is most likely to be caused by the haemodialysis procedure itsel f. Mechanical stress on the erythrocytes is believed to cause the 2,3- BPG to escape; it is then removed by haemodialysis. Physiologically, a n increase in 2,3-BPG would be expected to counteract the hypoxia whic h is frequently observed during haemodialysis. However, the present re sults show the opposite, a decrease in 2,3-BPG. No significant correla tion was shown between the haemoglobin concentration and the 2,3-BPG/H b(4) ratio before dialysis (p = 0.414). The pH showed a significant po sitive correlation with the 2,3-BPG/Hb(4) ratio before dialysis, where as the arterial pO(2) and the 2,3-BPG/Hb(4) ratio before dialysis were insignificantly negatively correlated. The concentrations of calcium, phosphate, creatinine, urea and-albumin did not correlate significant ly with the change in 2,3-BPG/Hb(4)-ratio after 1 h. The 2,3-BPG/Hb(4) ratio (p = 0.03) sampled just before dialysis correlated significantl y and positively with the total weekly dosage of erythropoietin given to the patients.