T. Weinstein et al., Haemolysis in haemodialysis patients: evidence for impaired defence mechanisms against oxidative stress, NEPH DIAL T, 15(6), 2000, pp. 883-887
Background. Uraemic patients have a decreased ability to withstand oxidativ
e stress. It is postulated that their antioxidant capacity is reduced, yet
the mechanism remains unclear. Recently 33 haemodialysis (HD) patients were
exposed to chloramine contamination in the water supply. This led to haemo
lysis in 24 patients, while nine were unaffected. In the former group haemo
globin decreased from 11.7+/-l.l to 8.5+/-1.4 g/dl (P<0.0001) and returned
to 11.4+/-0.9 g/dl (P<0.0001) following recovery. During haemolysis, haptog
lobin was 38.4+/-10.6 vs 138.1+/-8.3 ng/dl (P<0.0001) following recovery.
Methods. To explore the factors affecting the severity of haemolysis we stu
died extracellular and intracellular anti-oxidant defence mechanisms 3 mont
hs after recovery. In 29 patients and 20 controls we determined plasma glut
athione (GSH), and the erythrocyte enzymes glutathione peroxidase (GSH-Px),
glutathione reductase (GSH-Rx), and superoxide dismutase (SOD). Serum malo
ndialdehyde (MDA) was measured as a marker of oxidative stress.
Results. Plasma GSH was lower in patients as compared to controls (5.49+/-0
.26 vs 7.4+/-0.5 mu mol/l, P<0.005). There was an inverse correlation betwe
en GSH and the degree of haemolysis (r = -0.42, P<0.02). Patients had highe
r GSH-Rx (4.64+/-0.15 vs 3.97+/-0.12 U/gHb, P<0.02), lower GSH-Px (29.7+/-1
.85 vs 35.5+/-1.62 U/gHb, P<0.001), and similar SOD (0.63+/-0.02 vs 0.51+/-
0.02 U/mgHb) as compared to controls. There was no correlation between the
enzyme levels and the degree of haemolysis. MDA was higher in patients (2.3
7+/-0.07 vs 0.97+/-0.1 nmol/ml, P<0.0001). There was a correlation between
MDA and the years patients were on HD (r = 0.43, P<0.02).
Conclusions. These data indicate that HD patients have an impaired anti-oxi
dant response, which may be attributed in part, to plasma GSH deficiency. P
atients with the lowest plasma GSH levels are more susceptible to oxidative
stress and consequent haemolysis.