Study of urinary stone composition in a university-based hospital

Abstract

Objective: Knowing the composition of a urinary stone is valuable in its treatment, helping to define stone etiology, guide management, and prevent stone recurrence. This study aims to identify the incidence of various stone compositions in a university-based, tertiary care hospital. Material and Method: This retrospective study was conducted at King Chulalongkorn Memorial Hospital. Data of stone composition by infrared spectroscopy were collected from all patients undergoing upper urinary tract stone removal surgery from January 2015 to December 2018. Demographic data including age, gender, comorbidities, and stone characteristics were also collected. Results: A total of 173 stone analyses were included in this study. The main stone composition was calcium oxalate monohydrate (whewellite 49.7%), calcium carbonate apatite (dahllite 34.1%), calcium oxalate dihydrate (weddellite 5.2%), magnesium ammonium phosphate (struvite 4%), and ammonium hydrogen urate (2.9%). A small proportion of uric acid (1.7%), cystine (1.7%), and calcium phosphate (brushite 0.6%) was also found. No correlation was found between stone composition and age, gender or occupation. Multivariate analysis revealed that calcium oxalate stones were more common in males than females (odds ratio=2.21, 95%CI: 1.91-4.12; p-value=0.01). Phosphate-containing stones (struvite, dahllite and brushite) were more common in patients with a history of urinary tract infection (odds ratio=3.06, 95%CI: 1.18-7.92; p-value=0.02). Conclusion: Calcium oxalate and calcium carbonate apatite were the most common stone compositions found in this study. Male gender was a risk factor for oxalate stone, and a history of urinary tract infection was a risk factor for phosphate-containing stones.