Normalization of oxidative stress parameters after kidney transplant is secondary to full recovery of renal function.

Background: It is well-known that hemodialysis patients experience increased oxidative stress, which is believed to cause numerous uremia-related complications. Retention of water-soluble toxins as well as protein-bound toxins is due to renal failure. Kidney transplantation restores, at least partially, the fundamental processes of glomerular filtration which eliminates toxic solutes. The aim of this study was to determine the levels of several different glycoxydative stress-related parameters after kidney transplantation.

Patients And Methods: A cross-sectional study was carried out on 30 subjects: 10 kidney-transplanted patients with chronic renal failure (Tx-CRF), 10 kidney-transplanted patients with normal renal function (Tx-N) and 10 controls (Ctr). The groups were comparable with respect to age and gender. The following glycoxydative stress markers were determined by HPLC analysis: albumin-bound and free pentosidine, low-molecular weight-advanced glycation end products (LMW-AGEs), advanced oxidation protein products (AOPP) and low-molecular weight carbonyls (LMW-C). The total antioxidant serum capacity was monitored by measuring both the ferric reducing/antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC).

Results: With respect to the controls, the Tx-CRF patients had higher levels of pentosidine (2.66 +/- 0.98 vs 1.45 +/- 1.1 pmol/mg), LMW-AGE (47.55 +/- 39.74 vs 15.45 +/- 6.39 a.u./ml), and AOPP (6.71 +/- 0.78 vs 4.81 +/- 0.32 a.u./mg) while Tx patients with normal kidney function had levels of these compounds that were comparable to the controls, except for the LMW-AGEs which were higher. Levels of LMW-AGEs, pentosidine, LMW-C and AOPP were inversely correlated to creatinine clearance. The total antioxidation serum capacity was paradoxically higher in Tx patients than in the controls, regardless of kidney function. FRAP as well as ORAC, were correlated to uric acid (r = 0.62, p < 0.001; r = 0.54, p < 0.01).

Conclusions: The reported data indicate that kidney transplantation seems to restore a nearly normal level of glycoxidative stress markers, but a complete remission is only possible when the renal function is normal. An increase of total antioxidant power of serum in transplanted patients was reported, as probable effect of uric acid high levels.