Recent progress in molecular genetics have improved our understanding of the pathophysiology of several inherited diseases characterized by a renal hypokalemia. Some of these diseases result from inactivating mutations on the main cotransports involved in the reabsorption of sodium, namely the Gitelman and Bartter syndromes, that clinically mimics diuretic abuse with mild hypovolemia and low or normal blood pressure. Conversely some affections eventually lead to an increase in sodium reabsorption with hypervolemia and arterial hypertension: Liddle syndrome, apparent mineralocorticoid excess and dexamethasone suppressible hyperaldosteronism.