Faucon AL, et al. - In a prospective hospital-based cohort with chronic kidney disease (CKD) stage 1-4 (NephroTest Study), researchers assessed extracellular fluid (ECF) volume as a prognostic factor for CKD progression and mortality. They used the distribution volume and clearance of ⁵¹Cr-EDTA, respectively, to determine ECF (scaled to body surface area) and the measured glomerular filtration rate (mGFR). Overall 1593 patients were included with a mean age of 58.8 years. Men constituted 67% of the study sample. Mean mGFR and mean ECF was 43.6 mL/min/1.73m² and 15.1 L/1.73m², respectively. ECF was identified as an independent risk factor of CKD progression and death in this extensive cohort of carefully phenotyped CKD patients. For the clinical management of patients with non-dialysis CKD, the significance of close monitoring and treatment of fluid overload was underscored in this study.