Blood collection tube components interference on spectral signatures of chronic kidney disease probed by micro-reflectance Fourier-transform infrared spectroscopy on serum

Kidney disease is a worldwide public health problem, affecting between 8% and 16% of the global population. Chronic kidney disease is a silent disease and its detection is often late, making the treatment difficult. Actual diagnosis is based on dosage of canonical renal biomarkers like serum creatinine and observation of proteinuria/albuminuria which would be relatively insensitive to disease progression which usually is detected too late for any efficient therapeutic intervention. Besides, cardiovascular alterations and uremic toxins accumulation play a negative role in biological functions and lead to the main causes of death in a kidney damage situation. In this way, the development of options for real-time detection of kidney injuries is an urgent need. Considering the emerging Fourier-Transform Infrared spectroscopy (FTIR) as biophotonic resource for the biomedical sciences, we aimed to identify spectral signatures related to biomarkers of chronic kidney disease in human blood serum using micro-FTIR option. We investigated samples from 17 healthy individuals and 33 chronic kidney disease patients. Serum samples were analyzed by micro-reflectance FTIR and compared to routine blood and urinary exams (urinary creatinine, glucose, glycated hemoglobin, creatinine, urea, total proteins, albumin) outcomes. We notice that separator gel in VACUETTE® container tubes is a relevant source of spectral interference which decreased the accuracy of discrimination from 85% to 65%. Acquiring diluted gel signal as background would improve the discrimination performance in spite of some gel bands still present in samples data. 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 = O stretching of lipids, C = N stretching, CH bending vibration from the phenyl rings, N-H bending vibration coupled to C-N stretching, β-sheet of Amide II, and phenyl ring were modulated in blood serum samples of chronic kidney disease patients compared to healthy individuals. Urinary trypsin inhibitors, fatty acids, phenolic derivatives, tryptophan, and plasminogen were the biomolecules related to these assignments. In conclusion, micro-FTIR is a viable option for fast diagnosis of chronic kidney disease being also a powerful tool for monitoring the disease. We propose a method enabling large batches analysis, being eligible technology for clinical laboratories in healthcare facilities. However, for direct clinical applications ATR-FTIR would be the option of choice.