Mineral Density and Bone Metabolism in Patients with Nephrolithiasis

Kidney stone disease (KSD) is a disease characterized by the formation of stones in the urinary tract, kidneys, or bladder. Nephrolithiasis is a polyetiological disease, the development of which is influenced by hereditary, geographical, and dietary factors. Among the common risk factors for KSD are obesity, low fluid intake, excessive consumption of red meat, and low physical activity. However, unfortunately, there is still no consensus on the effect of calcium-containing foods and calcium supplements on the development of nephrolithiasis. This issue is particularly acute in the case of comorbid pathology associated with a decrease in bone mineral density (BMD) – osteoporosis (OP) and other metabolic bone diseases. Among the pathogenetic causes of OP there is increased bone resorption due to increased osteoclast activity, which can be assessed by determining markers of bone metabolism. Given the relevance of developing an approach to the prevention and treatment of comorbid pathologies – OP and KSD, we conducted a study to determine mineral density and bone metabolism indicators in patients with and without nephrolithiasis. The objective: to evaluate the peculiarities of changes in bone tissue, metabolism markers in patients with nephrolithiasis. Materials and methods. The study included 80 participants: 15 men (18.8%) and 65 women (81.3%). Patients were divided depending on the presence of KSD. Group I included 32 participants without KSD: women – 31 (96.9%), men – 1 (3.1%), median age 63.2 (58.8–67.4). Group II included 48 patients with KSD: women – 34 (70.8%), men – 14 (29.2%), median age 55.5 (51.5–62.5). The structural and functional state and markers of bone tissue metabolism were evaluated on the basis of the Ukrainian Osteoporosis Center of the SI “D.F. Chebotarev Institute of NAMS of Ukraine”, Kyiv, Ukraine (head: Prof. N. V. Grigorieva). Using X-ray absorptiometry. BMD was evaluated at the level of the lumbar spine, right femoral neck (RF), left femoral neck (LF), ultradistal forearm (UD). The TBS (texture analysis of DXA images of the lumbar spine, is an indicator of bone microarchitecture) iNsight method was used to assess the quality of bone tissue (Trabecular Bone Score – TBS). Among the bone markers, the levels of procollagen type I propeptide (P1NP), osteocalcin (OC), β-isomers of collagen type I C-terminal telopeptide (β-CTX), 25(OH)D, parathyroid hormone (PTH) and ionised calcium were determined. The results. The study showed that the percentage of BMD changes was comparable in both groups without a significant difference in the indicators in the comparison groups. At the same time, the TBS bone quality index was significantly lower in patients with established KSD. Metabolism of bone metabolism markers did not differ in the comparison groups, except for the level of PTH, which was significantly higher in patients with KSD (p = 0.017), but did not exceed the reference norms. Conclusions. Thus, no difference in BMD, but decrease the TBS index was found in the group of patients with nephrolithiasis. No difference was found between the indices of bone metabolism markers, phosphorus, calcium and vitamin D levels in the comparison groups, with a significantly higher level of PTH in patients with nephrolithiasis. The obtained data require further study of pathogenetic factors and their interrelationships in the development of nephrolithiasis and disorders of the quality of trabecular bone, as well as calculation of the risk of fractures in this category of patients.