Bioelectrical impedance vector analysis to evaluate relative hydration status

The objective was to present our clinical experience with bioelectrical impedance vector analysis (BIVA). Forty-six patients with chronic kidney disease (CKD) without oedema, 21 oedematous nephrotic children and 15 in remission from nephrotic syndrome were studied. The age range was 2–14 years. Data were obtained with the vector bioelectric impedance analysis method (Piccoli’s RXc graph with 95% confidence ellipses) and compared with normal paediatric values. The mean vector position differs significantly among the groups of evaluated patients (Hotelling T² test, p < 0.05). Mean vector position along the 45° direction (major axis of ellipses) indicates a progressive increase in body fluid volume from patients with CKD stage IV to stages II–III to patients in remission from nephrotic syndrome to oedematous subjects. We observed a progressive vector lengthening in children with severe renal disease (separate 95% confidence ellipse). This pattern indicates relative dehydration. BIVA represents a useful clinical tool that is able to detect changes in hydration.