Effect of Klotho (KL) protein and vitamin D parameters on stone recurrence

Introduction: Urinary tract stone disease (UTSD) continues to be an important health problem as the third most common pathological condition affecting the urinary system following urinary tract infections and prostate pathologies. One of the most important characteristics of UTSD is the recurrence risk, and recurrence occurs at a rate of 50% within 10 years and about 90% within 25 years. Alternative options are increasing day by day and becoming more noninvasive with the technological advances in the treatment of UTSD. Although these developments in treatment have high success rates and reduce morbidity associated with this disease, they do not affect the subsequent recurrence risk. This study aimed to evaluate the effects of α-Klotho which is an important regulator of calcium metabolism and the oxidative stress which is associated with multiple factors playing a role in the stone formation both on the urinary tract stone formation, for the first time, and on the stone recurrence, as well as their relationships with metabolic risk factors. Additionally, this study aimed to evaluate the use of these parameters as markers in the pathogenesis of stone formation and stone recurrence, and to determine the patients at risk in daily urology practice with the results obtained. In this prospective study, the roles of vitamin D parameters, age, BMI, occupation, socioeconomic level, education level, and dietary habits in the pathogenesis of urolithiasis and their effects on recurrent stone formation were also evaluated. Materials and Methods: 30 patients who were admitted to our clinic between July 2021 and October 2021 and diagnosed with recurrent urinary tract stone disease, 30 patients who were diagnosed with urinary tract stone disease for the first time, and a control group of 30 patients who did not have urinary tract stone disease and were similar to the patient groups in terms of age and gender were included in the study. Patients who were treated for stone disease were included in the study at least four weeks after stone removal and obstruction attack. Venous blood samples and 24-hour urine samples were taken for biochemical analysis after the survey form was filled by all individuals included in the study. Results: There was no difference in gender, age, BMI, daily calcium consumption, serum calcium and phosphorus levels, and urine pH distribution between the control group, the group with urinary tract stone disease for the first time, and the group with recurrent urinary tract stone disease. It was found that the control group had a significantly less animal food-based diet, a lower sedentary occupation rate, and a lower 24-hour urine calcium level compared to the group with the stone disease for the first time and the group with recurrent stone disease. No relationship was found between the increased vitamin D level and urolithiasis. A statistically significant difference was found in the α-Klotho level between the groups, and a relationship was found between the decreased α-Klotho levels and urinary tract stone formation. A statistically significant difference was found between the groups in terms of MDA and oxidative stress index level, and a relationship was found between increased MDA and OSI levels and the first-time and recurrent urinary tract stone formation. It was found that α-Klotho was determinant in the 24-hour urinary calcium level and OSI level. Conclusion: In addition to preventing stone formation by regulating calcium metabolism, α-Klotho was also found toplay a role in the pathogenesis of urolithiasis by suppressing oxidative stress. Our study demonstrated that α-Klotho and OSI can be used as a marker both in the pathogenesis of urinary tract stone formation and stone recurrence for the first time. It is predicted that biochemical markers and other factors detected in the pathogenesis of stone formation for the first time and the recurrent stone formation can be used in daily urology practice to determine patients at risk, and that they can contribute to providing early approach to patients at high risk and determining the frequency of medical treatment and follow-up. Regulation of abnormalities with lifestyle changes and medical approaches contributes to reducing the risk of stone formation and recurrence, preventing labor and socioeconomic losses, reducing morbidity and treatment costs due to the disease, and reducing the need for surgical intervention.