Metabolic Insights From Composition-Based Analysis of Kidney Stones: A Retrospective Study of 506 Patients

Background: Kidney stone disease is a highly prevalent condition with increasing global incidence and recurrence. The stone composition reflects underlying metabolic and biochemical alterations, and its evaluation may provide clinically relevant information for effective management. Aim: To evaluate the distribution of stone composition in a large surgical cohort and explore its association with routinely assessed metabolic parameters and recurrence patterns. Methods: This retrospective single-center study included 506 adult patients who underwent surgical stone removal between 2018 and 2024. The stone composition was determined using Fourier-transform infrared (FTIR) spectroscopy and classified as calcium oxalate monohydrate (COM), calcium oxalate dihydrate (COD), uric acid (UA), or a mixed type. Available serum (calcium, uric acid, glucose) and 24-hour urinary parameters (calcium, oxalate, citrate, uric acid) were evaluated. Subgroup analyses compared first-episode and recurrent stone formers. Results: A total of 506 patients were included in the final analysis. Calcium oxalate dihydrate (COD) was the most prevalent stone type, accounting for 307 cases (60.7%), followed by calcium oxalate monohydrate (COM) in 117 (23.1%), calcium/magnesium phosphate (CaP) in 46 (9.1%), uric acid stones in 31 (6.1%), and cystine stones in 5 patients (1.0%). The mean age of the cohort was 37.9 ± 11.4 years, and males comprised 73% of the study population. Patients with uric acid stones were significantly older than those with other stone types (p< 0.001), while body mass index did not differ significantly across stone groups (p> 0.05). Conclusion: Stone composition assessed by FTIR analysis demonstrates meaningful associations with selected metabolic abnormalities and recurrence status. Rather than functioning as a standalone decision tool, composition-guided interpretation combined with comprehensive metabolic evaluation may support more informed patient follow-up and preventive counselling. Keywords: calcium oxalate