Urolithiasis is a common, disturbing disease with high recurrent rate (60% in five years). Accurate identification of
urinary stone composition is important for treatment and prevention purpose. Our previous studies have demonstrated
that micro-Raman spectroscopy (MRS)-based approach successfully detects the composition of tiny stone powders after
minimal invasive urological surgery. But quantitative analysis of urinary stones was not established yet. In this study,
human urinary stone mixed with two compositions of COM, HAP, COD, and uric acid, were analyzed quantitatively by
using a 632.98 nm Raman spectrometric system.
This quantitative analysis was based on the construction of calibration curves of known mixtures of synthetically
prepared pure COM, HAP, COD and uric acid. First, the various concentration (mole fraction) ratio of binary mixtures
including COM and HAP, COM and COD, or COM and uric acid, were produced. Second, the intensities of the
characteristic bands at 1462cm <sup>-1</sup>(I<sub>RCOM</sub>), 1477cm<sup>-1</sup>(I<sub>RCOD</sub>), 961cm<sup>-1</sup>(IRHAP) and 1402cm<sup>-1</sup>(I<sub>Ruric acid</sub>), for COD, COM, HAP
and uric acid were used respectively for intensity calculation. Various binary mixtures of known concentration ratio were
recorded as the basis for the quantitative analysis. The ratios of the relative intensities of the Raman bands corresponding
to binary mixtures of known composition on the inverse of the COM concentration yielded a linear dependence. Third,
urinary stone fragments collected from patients after management were analyzed with the use of the calibration curve
and the quantitative analysis of unknown samples was made by the interpolation analysis. We successfully developed a
MRS-based quantitative analytical method for measuring two composition.
Urolithiasis is a common, disturbing disease with high recurrent rate (60% in five years). Accurate diagnosis of urinary
stone composition is important in preventing stone recurrence. With the improvement in minimal invasive urological
surgery, such as ureteroscopic lithotripsy, and extracorporeal shock wave lithotripsy, stone management becomes not so
suffering and effective than before. However, the new problem arises in that less and less stone fragments could be
collected because of tiny expelled stone powder after MIUS. The goal of this study is to use Raman spectroscopy (RS) to
analyze small stone fragments collected from urine of patients with urolithiasis after MIUS.
First, data from five main urinary stones [Calcium oxalate monohydrate (COM), Dicalcium phosphate dehydrate(DCPD),
Calcium phosphate hydroxide(hydroxyl apatite, or HAP), Calcium oxalate dehydrate(COD), and uric acid] were
established in RS database. Second, we used RS and clinical Fourier Transform Infrared Spectroscopy (FTIR) to analyze
stone fragments collected from patients with urolithiasis. Seventeen patients were enrolled in the study and all had
comparable results between RS detection and clinical analysis by FTIR.
RS approach has successfully detected tiny stone powders with or without fluorescence photobleaching. We successfully
measured COM, DCPD, HAP, COD, and uric acid stones. This study demonstrated the feasibility of using RS for conducting the clinical stone analysis from the tiny urinary stone sample. It provided satisfying results and could be applied on clinical practice.