MO929: Oxidative Stress in Hemodialysis Patients

It is known that chronic kidney disease (CKD) is associated with complications such as anaemia, mineral bone disorders (CKD-MBD) or diselectrolytemia.Therefore, the diet of renal patients is restricted in different nutrients such as potassium or phosphorus, a fact that could potentially increase oxidative stress [1]^. We investigated the relationship between an oxidative damage marker (malondialdehyde-MDA) on the one hand, and plasma antioxidant status (glutathione peroxidase-GPx) activity on the other hand with the nutritional status and with complications associated with CKD (anaemia, CKD-MBD).

We conducted a single-centre cross-sectional study that included 58 CKD G5D patients (mean age of 60.39 ± 11.73 years; 33 males, 25 females; mean haemodialysis vintage of 6.43 ± 4.89 years). All patients have been assessed regarding dialysis status (medical history). We performed analysis before the dialysis session using standard methods blood biochemistry, complete blood count and using spectrophotometry (HPLC)-malondialdehyde and glutathione peroxidase.

The studied patients’ mean malondialdehyde was 1.41 ± 0.42 mcmol/L, while mean glutathione peroxidase was 58.65 ± 12.15 U/g Hg. The oxidative stress markers did not show any statistically significant correlation with age, gender, dialysis vintage or with predialysis urea and bicarbonate. Patients with a BMI > 30 kg/sqm (21 versus 37 patients) showed a significantly higher level of MDA 1.57 ± 0.51 mcmol/L versus 1.31 ± 0.33 mcmol/L, P = 0.02. We have also found a negative statistically significant correlation between MDA level and serum K (r = –0.29, P = 0.02) and serum phosphorus (r = –0.29, P = 0.03). Patients with predialysis K of higher then 5.5 mEq/L had a statistically significant lower MDA (1.29 ± 0.4 mcmol/L versus 1.54 ± 0.4 mcmol/L, P = 0.025) and a non-significant higher GPx (59.0 ± 12.58 U/g Hg versus 58.2 ± 11.87 U/g Hg, P = 0.8). We found a negative statistically significant correlation of the MDA level with haemoglobin (r = –0.39, P = 0.002) and with haematocrit (r = –0.35, P = 0.006). No statistically significant correlation of the plasma antioxidant GPx with the studied parameters of anaemia and CKD-MBD has been found.

In our study, we found that increased oxidative stress (expressed through the malondialdehyde level) is associated with obesity and more severe anaemia. The indirect relationship found with serum K and phosphorus could indicate the risk of oxidative stress, and therefore it could be useful to take into account the dietary antioxidants when recommending low potassium and low phosphorus diet.