Body water distribution, early malnutrition and sarcopenia in ADPKD: insights from a cross sectional study

Background: Bioelectrical impedance analysis is a non-invasive method used to assess body composition and nutritional status in patients with chronic kidney disease (CKD). However, its reliability in autosomal dominant polycystic kidney disease (ADPKD) remains uncertain due to altered fluid distribution caused by cystic organ enlargement. This cross-sectional study compared bioelectrical impedance analysis-derived body composition and nutritional parameters between patients with ADPKD and those with non-ADPKD CKD. Methods: A total of 218 CKD patients (71 with ADPKD and 147 with non-ADPKD CKD, stages 1–5D) were enrolled. To control for baseline differences, 1:1 propensity score matching was applied. All participants underwent bioelectrical impedance analysis to assess body water compartments, skeletal muscle mass, fat mass, and phase angle. In the ADPKD group, parameters were further analyzed based on the presence of organomegaly, defined as nephromegaly (total kidney volume > 750 mL or kidney length > 16 cm) or hepatomegaly (liver transverse diameter > 25 cm). Results: After matching, two balanced groups of 71 patients each were compared. ADPKD patients showed significantly higher total and extracellular water than controls, both as absolute values normalized to height squared and as a percentage of body weight. Among ADPKD patients, the 41 with organomegaly had significantly lower phase angle, fat mass, fat-free mass, and skeletal muscle mass than the 30 without organomegaly—despite a paradoxical increase in body mass index (BMI). These changes were independent of kidney function. Conclusions: Bioelectrical impedance analysis detected altered fluid distribution and early signs of malnutrition and sarcopenia in ADPKD, supporting the need for proactive nutritional monitoring, especially in patients with organomegaly.