#1253

Staghorn Uric Acid Nephrolithiasis: Is Oral Chemolysis a Viable Alternative to Surgery?

V. Malkhasyan^1,2, S. Sukhikh¹, H. Tunguzbaev³, D. Pushkar³

¹Botkin City Clinical Hospital, Moscow, Russia
²Russia
³Russian University of Medicine, Moscow, Russia

Introduction:

Staghorn nephrolithiasis is considered one of the most challenging forms of urolithiasis. Traditionally associated with infection-related stones, staghorn calculi may also be composed of uric acid, particularly in patients with persistently low urine pH and radiolucent stones. While surgical approaches such as percutaneous nephrolithotomy (PCNL) remain the gold standard, oral chemolysis offers a non-invasive alternative in selected cases. This study aimed to evaluate the efficacy and safety of oral chemolysis using a citrate-based preparation in patients with presumed uric acid staghorn stones.

Material and methods:

A prospective, multicenter cohort study was conducted from January 2023 to October 2024, enrolling patients with radiologically suspected uric acid staghorn stones. Inclusion criteria were: urine pH ≤ 5.8, non-contrast CT stone density ≤ 650 Hounsfield units (HU), and radiolucency on urogram or topogram. Patients received oral chemolysis using a citrate mixture containing citric acid, potassium bicarbonate, and sodium citrate (commercially available as Blemaren). Patients were recruited from both outpatient clinics and hospital settings across Moscow. Stone composition was confirmed in cases requiring surgery.

Results:

Out of 49 enrolled patients, 2 were excluded during the initial follow-up. Complete stone dissolution was achieved in 30 patients (63.8%). The remaining 17 patients (36.2%) required surgical intervention. Of those who responded to therapy, 4 patients (8.5%) achieved complete dissolution within 1 month, 18 patients (38%) within 3 months, and 8 patients (17%) within 6 months. Among patients who proceeded to surgery, 12 stones (70.6%) were identified as calcium oxalate and 5 (29.4%) as uric acid. Thus, the proportion of patients with true uric acid stones who failed chemolysis was 14.3%. Stone density was the only parameter with a statistically significant impact on both the success of chemolysis and the likelihood of surgical intervention (p < 0.05). Regression analysis revealed that each unit increase in stone density reduced the probability of dissolution by a factor of 1.012, and increased the probability of requiring surgery by a factor of 1.008.