Central Diabetes Insipidus
Chloe de Crecy
Definition
- Lack of antidiuretic hormone results in free water excreted at kidneys.
Etiology
- Idiopathic, autoimmune, tumors (primary or secondary), infiltrative (Langerhans cell histiocytosis), congenital, trauma, surgery, severe shock/ischemia.
Presentation
- Polyuria, nocturia, polydipsia.
- Elevated Na and osmolality, only if impaired thirst. Can be normal due to compensatory thirst.
- Decreased bone mineral density (unclear pathophysiology).
Evaluation
- Confirm polyuria w/ low Uosm (DDx: psychogenic polydipsia, central DI, nephrogenic DI).
- Water restriction. If urine concentrates (Uosm>700), it is primary polydipsia not DI.
- Desmopressin trial (after Na >145) to differentiate between nephrogenic vs central. Central DI responds to desmopressin.
- MRI to investigate cause.
Management
- Desmopressin (ADH analog) - PO, IV forms. Given at bedtime to start; can add daytime doses to treat symptoms.
- Goal: reduce nocturia to improve sleep, reduce polyuria during the day to improve quality of life.
- Risk: hyponatremia
