Identification of molecular biomarkers in human serum for chronic kidney disease using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy

Chronic kidney disease (CKD) and its progression to end-stage renal disease (ESRD) represent significant global health challenges, contributing to increased morbidity and mortality. Despite the potential diagnostic value of ATR-FTIR spectroscopic analysis of serum in CKD, research in this area remains limited. This study addressed this gap by aiming to explore the spectral profiles of sera obtained from hemodialysis patients and healthy controls. We investigated serum spectral profiles from 21 hemodialysis patients and 21 age/sex-matched controls using ATR-FTIR spectroscopy in the mid-infrared region (4000-400 cm^-1). Spectroscopic analysis revealed elevated spectral intensity in ESRD samples compared to controls. Principal Component Analysis (PCA) successfully distinguished ESRD from control samples across multiple spectral regions (1480-900 cm^-1, 1800-900 cm^-1, and combined 3000-2800/1800-900 cm^-1). Partial Least Squares Discriminant Analysis (PLS-DA) demonstrated enhanced group separation, with the optimized PLS model achieving perfect classification metrics (100% accuracy, sensitivity, and specificity). The combined spectral region models exhibited superior diagnostic performance compared to other regions. The analysis identified key molecular biomarkers associated with ESRD, including alterations in lipids, protein structures (represented by amide I and II bands), carbohydrates, nucleic acids, and immunoglobulins, which correlate with known biochemical changes in CKD pathophysiology. These findings demonstrate that ATR-FTIR spectroscopy with multivariate analysis is a rapid, cost-effective screening tool for CKD. The identified spectral biomarkers provide insights into disease-related biochemical alterations, adding valuable data to the research in this field.