Differential diagnosis of the mineralogical composition of urinary stones

BACKGROUND: Urolithiasis is a common chronic disease with a high tendency to recurrence. The high rate of stone recurrence determines the clinical importance of metaphylaxis, which requires precise knowledge of the chemical composition of the calculi.

AIM: This work aimed to develop an optimal algorithm for mathematical processing of infrared spectra and differential diagnostic profiles of various mineralogical types of kidney stones.

METHODS: The object of the study comprised 115 kidney stones obtained during surgical treatment of patients with urolithiasis. Reference samples of the corresponding salts constituting kidney stones were used as standards. Pure reference substances were ground in an agate mortar with potassium bromide (KBr) crystals; the resulting mixture was compressed into transparent pellets, and infrared spectra were recorded using a Fourier-transform infrared spectrometer (Shimadzu IR Prestige 21, Japan). In the infrared spectra of the reference standards, the most frequently occurring and most intense absorption bands were selected (34 maxima).

RESULTS: For chemical compounds commonly present in urinary stones, two differential diagnostic profiles were constructed for each compound based on infrared spectral data. Visual comparison of the differential diagnostic profiles of urinary stones with the reference profiles allowed accurate identification of the chemical composition of the calculi in all cases.

CONCLUSION: Differential diagnostic profiles represent individual characteristics of each stone type and can be used to determine its chemical composition and to develop a personalized approach to the metaphylaxis of urolithiasis.