#1768 Decline of kidney function is associated with lower sweat weight in patients with chronic kidney disease

Abstract Background and Aims Excretion of sodium and water through the skin as sweat represents a regulatory mechanism of electrolyte- and fluid balance. Since patients with chronic kidney disease (CKD) exhibit increased skin sodium content, we investigated the feasibility of sweat testing as a novel experimental tool to provide a more complete assessment of fluid- and sodium status. Method In this cross-sectional feasibility study, we applied pilocarpine iontophoresis to induce sweat testing in 58 patients across various stages of CKD including kidney transplant recipients and a healthy control cohort (n = 6) to investigate possible effects of CKD and transplantation status on sweat weight and sodium concentration. Due to non-linear relationships, we modeled our data using polynomial regression. Results Decline of kidney function showed a significant association with lower sweat weight: adj R²= 0.2278, F(2, 61) = 10.29, P = 0.0001. Sweat sodium concentrations were increased in moderate CKD, however, this effect was lost in end-stage kidney disease: adj R² = 0.3701, F(4, 59) = 10.26, P = 2.261e-06. Conclusion Diagnostic sweat analysis represents an innovative, non-invasive option for a more thorough investigation of sodium- and fluid homeostasis in CKD. Lower sweat weight and higher sweat sodium concentrations represent a unique feature of CKD patients with potential therapeutic implications.