Association between serum albumin and body water using a bioelectrical impedance analyzer: a case report of longitudinal variation in a child with initial idiopathic nephrotic syndrome

Bioelectrical impedance analysis (BIA) is a commonly used noninvasive technique for body composition assessment with recently expanded indications. This reproducible measurement method uses electrical conductivity to evaluate body composition, including fluid status. In pediatric idiopathic nephrotic syndrome (INS), albumin leaks into the urine, resulting in dysregulated colloid-osmotic pressure in the blood vessels. This results in decreased circulating blood volume and edema. Blood tests are a useful evaluation method; however, it cannot be performed frequently in children because of their invasive nature. Herein, we present a case of a child with INS demonstrating a longitudinal correlation between serum albumin (S-Alb) levels and extracellular water (ECW)/total body water (TBW) ratio.