Advanced glycation end products: specific fluorescence changes of pentosidine-like compounds during short daily hemodialysis

Background: Advanced glycation end products (AGE) accumulate in uremia and represent an important etiopathogenetic cause of morbidity in dialyzed patients. Conventional hemodialysis treatment seems to be ineffective in lowering AGE levels. We wished to investigate whether daily hemodialysis (DHD), a treatment that seems to result in better clinical condition in end-stage renal disease patients, is effective in the reduction of these compounds. Methods: We evaluated 10 non-diabetic patients on standard hemodialysis (SHD = 3 x 4h/week) for more than 6 months by a crossover study. These patients were assigned randomly to 6 months of DHD (6 x 2h/week) or 6 months of SHD. Then, they were switched to 6 months of the alternative treatment. At the end of these two periods, we studied pentosidine-like AGE compounds by measuring the total fluorescence at a wavelength characteristic for these substances: Ex: 335nm / Em:385nm; we also measured protein-linked pentosidine at the same time points. Finally we determined the AGE-related total fluorescence in the deproteinized serum of 13 uremic patients on peritoneal dialysis (CAPD) and of 10 healthy controls. Results: Pre-HD AGE-related total fluorescence obtained after 6 months of DHD was significantly lower than that obtained with standard HD (DHD = 201.3 +/- 36.4 AU/ml vs. SHD = 267.5 +/- 141.4 AU/ml, p=0.03). The extraction rate per minute of dialysis was slightly, but not significantly higher during DHD than SHD (0.29 +/- 0.11% vs. 0.23 +/- 0.04, p = 0.07). AGE-related total fluorescence pre-HD values in patients treated by SHD and DHD were about 20-fold higher than in control subjects. They did not differ from CAPD patients. The pre-dialysis level of protein-linked pentosidine was significantly lower in DHD than in SHD (DHD = 16.12 +/- 4.71 pmol/mg protein, SHD = 22.64 +/- 6.86 pmol/mg protein, p < 0.01). Conclusions: DHD showed a reduction in AGE-related total fluorescence, although the mean value remained higher than in control subjects. DHD is also accompanied by a decrease in protein-linked pentosidine.