In this cross over salt-intervention study with quantification of ENaC the investigators refer to a published study regarding the sodium-chloride co-transporter (NCC) in the kidney, were rats where given aldosterone infusion or a low salt diet. In this study n=6 was sufficient to detect a 2-3 fold change in NCC in urinary exosomes. Furthermore 5 patients with primary aldosteronism had a significant increase in NCC in urinary exosomes (N. Lubbe et al, Hypertension 2012).