Purpose: Aim of the study was to identify long-term differences of middle and high-molecular-weight serum constituents under high- and low-flux hemodialysis treatments. Thus, the entire predialytic serum proteomes had to be analyzed using identical hemodialysis membrane material but with different cut-off values.
Methods and results: A cross-over study and a global native chromatographic proteomic approach were used to analyze serum compositions of 16 patients suffering from end-stage renal disease.
Results: No significant or reproducible differences were found between predialytic serum samples from high- and low-flux dialysis treatments using UV-absorbance and fluorescence spectrometry, PMF, or sequence tags. In contrast, there are characteristic differences in the predialytic serum composition of the patients considered and two control sets, which include samples obtained post-dialytically from patients and samples from healthy controls. Only a fraction of β2-microglobulin, an example of so-called middle molecules, exhibits the expected molecular weight. A small fraction was found with high molecular weight unaffected by any dialysis treatment. Moreover, immunoreactivity of fragments of β2-microglobulin, surprisingly, was also not affected by the cut-off of dialysis membranes.
Conclusions and clinical relevance: Thus, simply increasing the pore size of a hemodialysis membrane may not have any long-term effect on serum composition.