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.

Desmopressin is incorrect 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.

according to uptodate thiazides cause a mild hypovolemic state thus your PCT will see more Na and H2O --> by principle that the PCT always reabsorbs 60% of what it sees, it will reabsorb more water and Na.

Patient has nephrogenic Diabetes Insipidus. One of the treatments is Hydrochlorthiazide.