Changes of serum osteoprotegerin level in recurrent urolithiasis

Introduction. In our earlier research on the role of genetic factors in the development of recurrent urolithiasis, a significant relationship was found between the presence of single-nucleotide polymorphism rs3134057 in the osteoprotegerin (OPG) gene and the development of this disease. The above-mentioned single-nucleotide polymorphism is intronic, therefore, it is unable to involve the structure and functions of the OPG but to affect its expression. Thus, the study of serum OPG level may have diagnostic significance in recurrent urolithiasis. Objective. To study the relationship of serum OPG level with the presence of recurrent urolithiasis, as well as the effect of single nucleotide polymorphism rs3134057 on the OPG level. Materials & methods. One hundred and fifteen volunteers were included in the study from January 2021 to January 2022. Of the 115 participants, 45 (main group #1) were diagnosed with recurrent urolithiasis and localisation of the main stone in one of the ureters, 28 participants (main group #2) had previously suffered a single episode of acute renal colic followed by surgical treatment or stone self-discharge and were stone-free at the time of the study. Forty-two control group respondents were free of urolithiasis, including family history of urolithiasis. The serum OPG levels was determined by enzyme immunoassay using the Human OPG ELISA kit ab100617 ("Abcam plc", Cambridge, UK) according to the manufacturer's advice. Results. The analysis revealed that the serum OPG levels were significantly higher in the main group #1 than in the control group (median: 9.02 vs. 3.635, p = 0.012). When analyzing the relationship between the concentration of OPG in serum and the AA + AG genotype versus GG according to rs3134057 of the OPG gene, no statistically significant difference was found (p > 0.05). The same result was obtained when comparing groups with AA vs. AG vs. GG genotypes (p > 0.05). Conclusion. The present study showed that an increased serum OPG level in patients with recurrent urolithiasis may indicate the presence of a relapse of the disease. Further study in large samples will finally confirm the significance of OPG as a marker of relapse, including in genetically determined forms.