A 42-year-old man comes to the physician because of ...
Where in Pathoma? I couldn't find it.
hydrocholorothiazide is DOC for Nephrogenic Diabetes insipidus because it paradoxically causes an increase in BP by increasing sodium absorption and thus water absorption, Pathoma explains this nicely.
Also you shouldn't have chosen Desmopressin because upon fasting (fluid restriction) ADH is increased meaning ADH is being released Centrally but is not working in the kidneys at the V2 receptors of the epithelial renal cells at Collecting duct.
On that note, Amiloride is used for Lithium induced nephrogenic DI.