Can the Total Body Water and Total Fat Mass Predict Kidney Stone Recurrence in Overweight and Obese Patients?

Background Urolithiasis prophylaxis is a cornerstone for kidney stone formers. Obesity is a well-known risk factor for kidney stone recurrence. The objectives of this research were to highlight the correlations between the mean water intake and free water deficit (FWD) depending on plasma Na and weight. Methods Anthropometric and nutritional analysis was performed using a body analyzer with magnetic bioimpedance ankle-to-foot, which determined the total percentage of water in the body. Results The mean age was 52.19 years old and the mean body mass index (BMI) was 33.68 km/m². About 58.23% (n=46) of patients declared at least one episode of urolithiasis in their pathological antecedents. The patients were counseled by a dietician and lost weight. After losing weight, the total body water (TBW) percentage increased (average=41.37%), while the total fat percentage decreased (average=33.52%). Urinary volume increased, but the water did not accumulate for proper hydration. This may explain the recurrence of urinary stones despite large amounts of water intake. Conclusions The present study indicates an inverse-proportional relationship between TBW and fat mass (FM). Obese patients with lithiasis should lose weight due to total FM, not TBW.