Biochemical fingerprinting of peritoneal dialysis effluent according to PET-defined transport characteristics using FTIR spectroscopy

Peritoneal equilibration test (PET) assesses peritoneal membrane transport but provides limited information on the biochemical composition of peritoneal dialysis (PD) effluent. This study used Fourier-transform infrared (FTIR) spectroscopy to characterize effluent across PET-defined D 4 /D 0 glucose-based and peritoneal solute transport rate (PSTR) categories. In this single-center, cross-sectional study, effluent was collected from routine dialysis exchanges immediately preceding PET, rather than from the PET dwell itself, and analyzed using FTIR spectroscopy. PET was performed separately using a modified protocol with 4.25% glucose. Six predefined functional-group regions—O–H/N–H stretching, C–H stretching, amide I, amide II, C-H bending, and carbohydrate-associated vibrations—were quantified as normalized integral-area ratios and compared across transport categories. Fifty-three patients receiving continuous ambulatory PD were enrolled (mean age 55.4 ± 13.6 years; mean PD vintage 39.4 ± 30.0 months). Visual differences in mean spectral intensity were observed, with low-average and low groups generally showing higher absorbance than high-average and high groups. However, none of the six regions differed significantly among categories under either classification. These descriptive spectral patterns did not establish the ability of FTIR spectroscopy to discriminate among PET-defined transport groups. Further whole-spectrum multivariate and longitudinal studies are needed to evaluate its clinical utility.