Snapshot A 30-year-old woman presents to her primary care physician for increased frequency of urinating, thirst, and urinating at night. She was in a car accident about a month ago, where she had head trauma. Since then, she reports that she has noticed this increased frequency of urination. At that time, head imaging had been normal. Her physician decides to conduct a vasopressin challenge. The results show decreased urine volume and increased urine osmolality. Based on these results, she decides to start the patient on desmopressin. (Central diabetes insipidis) Introduction Clinical definition login to view 2 more bullets Central vs Nephrogenic Diabetes Inspidus (DI) Central DI Definition Failure to produce antidiuretic hormone (ADH) Insensitivity or resistance of the kidneys to ADH in the collecting duct Etiology Pituitary tumor, where vasopressin is released Other pituitary injuries autoimmune disease trauma surgery ischemia Drugs lithium demeclocycline amphotericin B Congenital (rare) Electrolyte abnormalities hypercalcemia hypokalemia Pathogenesis ↓ ADH, resulting in increased extracellular fluid osmolarity ↑ADH Vasopressin (DDAVP) challenge ↓ Urine volume and ↑ urine osmolality No change in urine volume or osmolality Presentation Symptoms login to view 4 more bullets Studies Serum labs login to view 3 more bullets Other tests login to view 12 more bullets Differential Primary polydipsia login to view 3 more bullets Treatment Lifestyle login to view 3 more bullets Medical login to view 22 more bullets Complications Hypernatremia Dehydration