REN and Hyponatremia: The mechanisms of RAAS inhibitor (ACEIs and ARBs)-related hyponatremia may involve reduced sodium reabsorption due to the down-regulation of epithelial sodium channels in the distal nephron, particularly in the distal convoluted tubule, connecting tubule, and cortical collecting duct, the suppression of renin expression in renal tubular cells despite a compensatory increase in systemic renin, and the inhibition of angiotensin II-mediated aldosterone secretion [34,40].