Can urine osteopontin levels, which may be correlated with nutrition intake and body composition, be used as a new biomarker in the diagnosis of nephrolithiasis?

Background And Aim: The nephrolithiasis has a multifactorial etiology resulting from the interaction of metabolic, genetic and environmental factors. Parameters such as nutrition and urinary osteopontin (OPN) level may affect kidney stone formation. The purpose of this study is to evaluate the correlation between urinary OPN level and kidney stone formation and effect of nutrition on OPN level in nephrolithiasis.

Materials And Methods: This study was conducted on 88 volunteers including 44 healthy individuals and 44 patients diagnosed with nephrolithiasis and aging between 20 and 65 years. Some serum parameters and urinary OPN levels of the individuals were analyzed. Several anthropometric measurements of the individuals were taken and calculated their body mass index. Additionally, 24-hour dietary recall and water intakes were recorded and the participants completed food-frequency questionnaire for the evaluation of their nutritional status.

Results: Urinary OPN (ng/mL) levels of patients were lower than that of control group (p<0.05). Dietary energy, carbohydrate, poly-unsaturated fatty acid (PUFA) and n-6 fatty acids intakes and urinary OPN levels of male patients were positively correlated (p<0.05). Additionally, there was a negative correlation between their urinary OPN (ng/mL) and serum creatinine (mg/dL) levels of female patients (p<0.05). Body weight, waist circumference, hip circumference and body muscle mass values of healthy males were positively correlated with their urinary OPN levels (p<0.05).

Conclusions: Results of the study showed that low urinary OPN levels were correlated with increased kidney stone risk, and dietary habits can affect urinary OPN level.