Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy as a bedside diagnostic tool for detecting renal disease biomarkers in fresh urine samples

Attenuated total reflection (ATR)-FTIR spectroscopy is a convenient technique for analysing biomedical samples because of its sensitivity to subtle compositional changes, speed of data acquisition and ease of sample preparation. We have applied the technology to the detection of disease biomarkers in urine and investigated the translation of these diagnostic methods to simple bench-top spectrometers. To demonstrate the use of ATR-FTIR spectroscopy as a bedside diagnostic tool, we have installed a roomtemperature bench-top infrared spectrometer in the renal unit at the Royal Free Hospital (RFH), London. A nurse recorded spectra of urine from patients with a range of conditions, including diabetes, kidney disease, stone disease and urinary tract infections, and the data were correlated to medical conditions to assess the diagnostic capabilities of the system and to identify potential spectral patterns associated with disease. Two hundred and six spectra have been recorded to date; these show it is possible to detect urea, creatinine, protein, lipids, sugars and other minor metabolites, including potential disease biomarkers. Several spectral peaks of potential diagnostic interest were identified that show variations between normal and disease samples.