Staghorn uric acid stones: oral chemolysis outcomes and development of a nomogram for treatment success.

Oral chemolysis is an established non-surgical treatment for uric acid nephrolithiasis, but prospective data on its efficacy in staghorn calculi remain limited. This prospective study included 51 patients who underwent oral chemolysis with citrate mixtures. Baseline clinical, laboratory, and native computed tomography parameters were analyzed. Treatment response was assessed by follow-up imaging at 1, 3, and 6 months. The primary endpoint was complete stone dissolution. Logistic regression was used to identify independent predictors and develop a predictive nomogram. Complete stone dissolution was achieved in 33 patients (64.7%). Surgical treatment was required in 17 patients (33.3%). One patient (2.0%) discontinued therapy due to worsening comorbidities, did not undergo surgery, and was included in the final analysis as a treatment failure. Patients with complete dissolution had lower stone density and smaller baseline stone volume than non-responders. In multivariate analysis, both stone density and baseline stone volume independently predicted complete dissolution. Each 100 HU increase in stone density reduced the odds of complete dissolution (OR 0.42; 95% CI 0.18-0.98; p = 0.046), as did each 1 cm³ increase in baseline stone volume (OR 0.86; 95% CI 0.76-0.97; p = 0.011). The nomogram demonstrated good discriminatory performance, with an AUC of 0.796. Oral chemolysis may be an effective non-surgical option for selected patients with suspected staghorn uric acid nephrolithiasis, and baseline stone density and volume may help predict treatment success.Trial registration: ClinicalTrials.gov, NCT07162974, August 19, 2025.