Spectrum of urinary stone composition in Northwestern Rajasthan using Fourier transform infrared spectroscopy.

Introduction: The aim of this study was to evaluate the chemical composition of urinary stones and pattern of changes according to the patient's age in Northwestern Rajasthan using Fourier transform infrared (FTIR) spectroscopy.

Materials and Methods: A prospective study of 1005 urolithiasis patients was carried out in two tertiary care centers from September 2012 to September 2016. Chemical composition of urinary stones was analyzed using FTIR spectroscopy, and a subgroup study based on the patient's age was done (8-12 years - Group A, 13-18 years - Group B, and >18 years - Group C).

Results: Out of 1005 patients, 59 were in Group A, 104 in Group B, and 842 in Group C. Male predominance was found in all age groups. Mixed composition stones were much more common than pure one (74.83% vs. 25.17%). Overall, combination of calcium oxalate monohydrate with dihydrate was the most common composition (58.0%). Calcium oxalate was the predominant chemical composition in 91.54% of stones, followed by uric acid in 4.28%, struvite in 2.29%, calcium phosphate in 1.49%, and cystine in 0.4%. The proportion of calcium oxalate stone was increasing while that of struvite, uric acid, and cystine stone was decreasing with age. Most of the vesical calculi in pediatric age group (Group A; 8-12 years) patients were made up of combination of struvite, calcium phosphate, and uric acid. A total of 85.11% of staghorn calculi were of oxalates.

Conclusion: In Northwestern Rajasthan, calcium oxalate is the most common composition of urinary stones in all age groups. Mixed stones are more common than pure ones. The incidence of calcium oxalate stone increases while that of struvite, uric acid, and cystine stone decreases with age.