Aldosterone
Most important adrenal cortex hormone for the regulation of salt metabolism (mineralocorticoid).
Its biosynthesis is mediated by the adrenocorticotropic hormone (ACTH) from the anterior pituitary. Aldosterone stimulates Na+-reabsorption and K+-secretion in the salt-transporting cells of the kidney and leads to retention of Na+ and increased excretion of K+ throughout the body.
The secondary result is water retention, and thus an increase in extracellular volume.