Metabolic abnormalities in pure vs. mixed struvite stone formers: A retrospective comparative analysis utilising large language models for data extraction

Objectives

To evaluate demographic characteristics and the prevalence of metabolic abnormalities in patients with pure struvite stones compared to those with mixed struvite and calcium oxalate stones.

Methods

We retrospectively reviewed 3001 stone analyses performed at our institution between August 2019 and April 2024. Patients who had a 24-hour urinary stone risk profile within six months of stone analysis were included. Exclusion criteria were a history of nephrolithiasis, bladder stones, neurogenic bladder or surgery for encrusted stent removal. Demographics, comorbidities and laboratory values were extracted using a HIPAA-compliant pipeline enhanced with a large language model (LLM). Patients with pure struvite stones were compared to those with mixed calcium oxalate–struvite stones. Statistical analysis was performed using RStudio v4.1.3.

Results

Forty-one patients met the inclusion criteria: 21 with pure struvite stones and 20 with mixed stones. While pure struvite stones were more common in females, the difference was not statistically significant. Demographics and comorbidities were similar between groups. Patients with pure struvite stones showed lower urinary levels of oxalate, potassium, citrate and uric acid, though not statistically significant. However, supersaturation of brushite, calcium oxalate and sodium urate was significantly lower in the pure struvite group (P < 0.05). At least one metabolic abnormality was present in 90.5% of the pure struvite group and in all patients with mixed stones.

Conclusions

Metabolic abnormalities are highly prevalent in both pure and mixed struvite stone formers. These findings support routine metabolic evaluation in patients with infection-related stones to guide long-term management.