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- A condition in which there is reduced ability to concentrate the urine due to impaired reabsorption of water in the renal collecting tubules
- It is characterized by polyuria and, in sensate patients, pronounced thirst.
- Two main forms of diabetes insipidus (DI) are known. Central diabetes insipidus (CDI) represents vasopressin (antidiuretic hormone [ADH]) deficiency. Nephrogenic diabetes insipidus (NDI) represents target end organ (renal tubule) unresponsiveness to vasopressin/ADH. Rarely, DI can be induced by pregnancy, known as gestational diabetes insipidus (GDI).
- System(s) affected: endocrine/metabolic/renal
- DI occurs in 3/100,000 persons in the general population.
- Vasopressin deficiency (CDI) may occur at any age and has no gender preference.
- NDI in children is most often congenital and usually manifests during infancy.
- The most common causes of acquired NDI are long-term lithium therapy and chronic hypercalcemia.
- Pediatric NDI is encountered in males more commonly, reflecting its X-linked recessive mode of inheritance.
- CDI: 1 in 25,000 persons
- NDI: unknown
- GDI: 2 to 6 in 100,000 pregnancies (1)
Etiology and Pathophysiology
- Inadequate secretion of vasopressin may be due to loss or malfunction of the neurosecretory cells of the neurohypophysis (posterior pituitary) and the pituitary stalk.
- Posterior pituitary lesions rarely cause CDI because ADH is produced in the hypothalamus and therefore, still may be secreted above the level of injury.
- Collecting tubule fails to reabsorb water effectively from filtrate due to ADH deficiency or absence.
- Can be complete or partial
- Trauma/head injury: A study of 89 patients with traumatic brain injury found that primary hormonal dysfunction (including DI) occurred in 21% of patients and tended to occur in patients with the lowest Glasgow Outcome Scale scores (2).
- Neurosurgery: A study of 102 consecutive craniopharyngioma surgeries found that postoperative DI is more common in children than adults (80% vs. 63%), with higher incidence of permanent DI in children (55.6%) (3).
- Tumors (e.g., craniopharyngioma, lymphoma, metastasis)
- Infections (e.g., meningitis, encephalitis)
- Infiltrative diseases (e.g., sarcoidosis, histiocytosis)
- Hypoxic encephalopathy
- Vascular disorders
- Congenital: Brain dysmorphisms may be identified in up to a quarter of children with CDI (4) but recognizable heritable defects only in 1–2%.
- Target organ (renal) unresponsiveness to vasopressin
- Reabsorption of water from filtrate in collecting tubules is impaired despite presence of ADH.
- Can be complete or partial
- Drug-induced (amphotericin B, colchicine, demeclocycline, foscarnet and other antivirals, aminoglycosides, lithium carbonate, loop diuretics, methoxyflurane). Inappropriate or excessive use of vasopressin antagonists such as tolvaptan mimics NDI.
- Heritable defects, including X-linked V2 receptor gene mutation and autosomal recessive aquaporin-2 gene mutation
- Electrolyte disorders, especially hypercalcemia and hypokalemia
- Renal tubular disorders
- Partial ureteral obstruction and postobstructive state
- Intracranial neoplasm
- Intracranial surgery (especially pituitary)
- Medications (amphotericin B, colchicine, demeclocycline, antiviral agents, aminoglycosides, lithium, loop diuretics, methoxyflurane)
- Head trauma
- Genetic predisposition
Commonly Associated Conditions
- Potassium depletion
- Chronic hypercalcemia
- Renal amyloidosis
- Tubulointerstitial nephritides
- Sjögren syndrome
- Sickle cell anemia
- Multiple myeloma
- Developmental delay (in congenital NDI)
- Tumors (primary and metastatic)
- Infections (encephalitis, TB, syphilis)
- Wolfram syndrome (DIDMOAD: DI, diabetes mellitus, optic atrophy, deafness)