Snapshot A 45-year-old woman presents to her primary care physician for persistent thirst. She has a past medical history of bipolar disorder and hypertension. She reports that the thirst began 4 weeks ago, along with increased trips to the bathroom. Her young cousin was recently diagnosed with diabetes after similar symptoms, and she is worried that she has diabetes. On physical exam, she has dry mucous membranes. A closer look at her medication list shows a new medication, lithium, started about 8 weeks ago. (Nephrogenic diabetes insipidus) Introduction Clinical definition diabetes insipidus (DI) characterized by excess free water loss and dilute urine Central vs Nephrogenic Diabetes Inspidus (DI)Central DINephrogenic DIDefinitionFailure to produce antidiuretic hormone (ADH)Insensitivity or resistance of the kidneys to ADHEtiologyPituitary tumorOther pituitary injuriesautoimmune diseasetraumasurgeryischemiaDrugslithiumdemeclocyclineamphotericin BCongenital (rare)Electrolyte abnormalitieshypercalcemiahypokalemiaPathogenesis↓ ADH↑ADHVasopressin (DDAVP) challenge↓ Urine volume and ↑ urine osmolalityNo change in urine volume or osmolality Presentation Symptoms polyuria polydipsia nocturia thirst Studies Diagnostic testing studies 24-hour urine studies login to view 4 more bullets water deprivation challenge login to view 1 more bullet vasopressin challenge login to view 4 more bullets electrolytes login to view 1 more bullet Differential Primary polydipsia distinguishing factor hyponatremia after trial of desmopressin decreased urine output with water deprivation test Treatment Management approach treat underlying cause when appropriate remove offending agent if possible Central DI first-line desmopressin (DDAVP) login to view 2 more bullets other hydration Nephrogenic DI first-line hydrochlorothiazide login to view 2 more bullets indomethacin login to view 2 more bullets amiloride login to view 4 more bullets other hydration low-sodium diet Complications Hypernatremia Dehydration