The study aims to provide quantitative facts on the pathophysiological changes in tissue Na+ content during Na+/K+ redistribution disorders in patients with PA in response to standard therapy. The investigators hypothesize that patients with primary aldosteronism have excessive Na+ storage in the muscle, which can now be quantified non-invasively using 23NaMRI. In analogy to the role of HbA1c as a metabolic long-term marker in diabetes, the quantifiable changes in muscle Na+ content may deliver the data evidence necessary to justify and conduct randomized diagnostic endpoint outcome trials in the future, with the ultimate aim to improve PA detection rate and treatment.