Assessment of Renal Injury and Inflammation: Diagnostic Implications of Serum Cystatin C and IL-18 in Urolithiasis

Abstract

Background: Kidney stones is a prevalent and recurrent condition associated with significant morbidity. While traditional risk factors are known, the roles of subclinical renal dysfunction and inflammation in its pathogenesis are still being explored. This study aimed to evaluate serum Cystatin C (Cys-C) as a marker of renal function and Interleukin-18 (IL-18) as a pro-inflammatory marker in patients with kidney stones, and to assess their correlation with conventional biochemical markers.

Methods: In this case-control study, 60 patients with a confirmed diagnosis of nephrolithiasis and 60 age- and sex-matched healthy volunteers were enrolled. Serum levels of Cys-C and IL-18 were quantified using enzyme-linked immunosorbent assay (ELISA). Serum Ca⁺², P, and UA levels were measured using a clinical chemistry analyzer. Statistical analyses were performed to compare the biomarker levels between the two groups.

Results: The patient group demonstrated significantly higher serum levels of Cys-C (0.363 ± 0.11 vs. 0.301 ± 0.08, P<0.001) and IL-18 (10.03 ± 4.98 vs. 7.22 ± 2.22, P<0.001) compared to the healthy control group. Patients with nephrolithiasis also had significantly elevated levels of UA (7.02 ± 1.77 vs. 4.80 ± 1.35, P<0.001), Ca⁺² (9.91 ± 0.91 vs. 9.01 ± 0.68, P<0.001), and phosphorus (4.88 ± 1.04 vs. 3.44 ± 0.71, P<0.01). Within the patient group, there were no significant differences in these biomarker levels based on sex or age.

Conclusion: The significant elevation of Cys-C and IL-18 in patients with nephrolithiasis suggests that subclinical renal dysfunction and pro-inflammatory processes are key components of the disease's pathophysiology. These markers, in conjunction with traditional stone-forming minerals, may serve as a valuable panel for assessing disease activity and renal involvement in patients with kidney stones.