749 Components in blood collection tubes interfere with the spectral signatures of patients with kidney disease: analysis by infrared microspectroscopy

Abstract Background and Aims Kidney disease is a worldwide public health problem, affecting between 8%-16% of the global population. Chronic Kidney Disease (CKD) is a silent disease and its detection is often late, making the treatment difficult. Considering the emerging Fourier-Transform Infrared spectroscopy (FTIR) as a biophotonic resource for the biomedical sciences, we aimed to identify spectral signatures related to biomarkers of CKD in human blood serum using the microscopy FTIR option. Method Blood serum samples from 17 healthy in comparison to 33 CKD patients were analyzed by micro-reflectance FTIR spectroscopy. The first aspect to be addressed refers to the possible influence of components present in the container tube. Here we showed that separator gel in VACUETTE® tubes is a relevant source of spectral interference which could decrease the accuracy of discrimination from 85% to 65%. Acquiring a diluted gel signal as a background would improve the discrimination performance in spite of some gel bands still present in sample data. Results In this case, our results indicated that vibrations associated with galactose-4-sulfate, CH2 bending of the methylene chains, C=C in lipids and fatty acids, C=N stretching, CH bending vibration from the phenyl rings, N-H bending vibration coupled to C-N stretching and β-sheet of Amide II and ring base are modulated in blood serum samples of chronic kidney disease patients compared to healthy patients. Urinary trypsin inhibitors, fatty acids, phenolic derivatives, tryptophan, and plasminogen were the biomolecules related to these assignments were the biomolecules related to these assignments. Conclusion In conclusion, FTIR is a viable option for fast diagnosis of chronic kidney disease being also a powerful tool for monitoring the disease. Due to its capability of large batch analysis, the micro-FTIR would be an eligible technology for clinical laboratories in healthcare facilities. However, for direct clinical applications, ATR-FTIR would be the option of choice. Figure 1: a) Average FTIR spectra for blood serum samples from Control (black line) and chronic kidney disease (CKD, red line). Solid and dashed lines data refer to acquisition considering gel and air background, respectively. Spectra were vertically translated to become comparable. b) FTIR spectra of water dissolved in gel (blue) compared to Control average spectrum in the 1015-1210 cm⁻¹ region. It is clear the redshift of Control spectra referred to W