Evaluating the role of urine chemistry in shock wave lithotripsy outcomes

Extracorporeal Shock Wave Lithotripsy (ESWL) is a commonly used method for the noninvasive treatment of kidney stones. However, achieving optimal treatment outcomes and minimizing potential damage to the kidney necessitates careful consideration for the total amount of energy utilized. This study aims to investigate whether urine pH and urine specific gravity have an impact on the total amount of energy applied during SWL.

Between January 2023 and December 2023, 129 patients with renal stones underwent SWL in our department using the Storz Medical Modulith Inline lithotripter. Stone-free rates, complications, and the impact of patient, urine, and stone characteristics on energy use were analyzed. Urine samples were analyzed for pH and specific gravity. Stone characteristics, including size, HU, and skin-to-stone distance, were recorded. The obtained data were evaluated regarding the possible relationship between the total energy amount (determined as a risk factor) and the age, BMI, urine pH, urine specific gravity, stone size, HU, and skin-to-stone distance by using the Pearson correlation coefficient. p-value of < 0.05 was considered statistically significant.

Evaluation of our findings revealed a negative linear relationship between total amount of energy used and the urine pH, indicating a decrease in the total energy amount as urine pH shifts towards alkaline values (p = 0.038; p < 0.05). However, no statistically significant relationship was observed between age, BMI, urine specific gravity, stone size, HU, and skin-to-stone distance and the total energy amount.

Our findings demonstrated a significant relationship between urine pH and the total amount of energy applied during SWL sessions, suggesting the need for further prospective research to better understand the possible association between these two parameters. Such investigations could contribute to the development of more reasonable and effective strategies for kidney stone treatment in an attempt to minimize the potential kidney damage.