The study aimed to investigate the changes in the concentration of bikunin, osteopontin, and nephrocalcin, depending on the changes in the renal stone-forming activity in patients with recurrent urolithiasis.
Materials and methods. The study comprised 152 patients with recurrent calcium oxalate stones at various localizations. Patients of the study group (n=78) were administered complex preventive treatment (water load, Blamaren, thiazide diuretics, oral calcium supplementation) aimed at reducing the activity of urolithiasis. Patients of the control group (n=74) received no treatment. The studied parameters included concentrations of urine bikunin, osteopontin, and nephrocalcin in using ELISA. The follow-up period was six months.
Results. By the end of the follow-up, the bikunin concentration in the control group was significantly higher than in the study group (7.0±0.81 mg/ml vs. 3.28±0.86 mg/ml, respectively, p<0.05) while osteopontin level was significantly lower (2.4±0.39 mg/ml vs. 3.4±0.36 mg/ml, p<0.05). The nephrocalcin concentrations during the follow-up period did not change significantly (p>0.05). The presence of hypercalciuria did not lead to significant changes in the concentration of stone formation inhibitors.
Discussion. The increase in bikunin concentration in control patients is associated with an increase in the expression of this stone formation inhibitor due to the rise in the urolithiasis activity. Reduction in the osteopontin concentration in patients with high urolithiasis activity is a consequence of osteopontin being a constituent of calcium oxalate stones.
Conclusion. In patients with calcium oxalate urolithiasis, testing for urine concentrations of bikunin and osteopontin as potential markers can be used to estimate the risk of stone recurrence.

Keywords: recurrent urolithiasis, markers of urolithiasis, bikunin, osteopontin