Diabetes insipidus and polyuria-polydipsia — viva

Opening (must-hit)

"This is the polyuria-polydipsia syndrome: constant polyuria with polydipsia and a normal glucose, so a water diuresis. Her high-normal sodium and osmolality with dilute urine keep true diabetes insipidus in view. I need to separate three diagnoses — central diabetes insipidus, nephrogenic diabetes insipidus, and primary polydipsia — using paired osmolalities and either a water-deprivation test with a desmopressin challenge or, preferably, a copeptin-based test. Treatment then follows the mechanism: desmopressin for central disease, a low-solute diet with thiazide, amiloride and indometacin for nephrogenic disease, and fluid restriction for primary polydipsia." ^[1][5]