Contribution of Fourier transform infrared spectroscopy to the identification of urinary stones and kidney crystal deposits

Abstract

Crystal-induced kidney disease is a frequent occurrence in human pathology. It is becoming more and more apparent that knowledge of kidney stone composition and structure appears to be the key for establishing the etiology of stone disease. A number of analytical methods may be applied to stone analysis, but only a few of them are able to quickly and easily provide extensive information on both stone structure and composition relevant for clinical diagnosis. More than 12,000 calculi were analyzed using a combination of microscopic examination, sequential infrared (IR) analysis by Fourier transform infrared spectroscopy (FTIR) of each part of stone, and quantification of all components present. We also investigated 50 biopsies using FTIR microscopy. Our results confirm that IR spectroscopy is a reliable and accurate technique for both molecular and crystalline identification. Some limitations of standard procedures, because of very small samples or due to absorption band overlap, can be solved using FTIR micromethod or a particular method like IR microscopy. In such cases, the spectrum identification must be conducted in different manners. Until now, spectral identification procedures based on computerized spectra libraries must be used with caution because of false results, mainly for mixtures of mineral compounds. Trained eyes always provide the best results for reading spectra from common stones. In routine practice, accurate identification of all components present in calculi is necessary for understanding urolithiasis mechanisms, but only semiquantitative assessment is sufficient to guide physicians toward establishing correct etiology. © 1997 John Wiley & Sons, Inc. Biospectroscopy 3: 347–369, 1997