Diabetes Insipidus

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Basics

Description

  • 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

Epidemiology

Incidence
  • 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.

Prevalence
  • CDI: 1 in 25,000 persons
  • NDI: unknown
  • GDI: 2 to 6 in 100,000 pregnancies (1)

Etiology and Pathophysiology

  • CDI
    • 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
    • Etiology:
      • 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%.
  • NDI
    • 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
    • Etiology:
      • 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
  • GDI
    • Placentally-produced vasopressinase shortens half-life of vasopressin in circulation (1).
    • It is usually a transient condition but is commonly undiagnosed (1).

Risk Factors

  • Intracranial neoplasm
  • Infection
  • Intracranial surgery (especially pituitary)
  • Medications (amphotericin B, colchicine, demeclocycline, antiviral agents, aminoglycosides, lithium, loop diuretics, methoxyflurane)
  • Head trauma
  • Genetic predisposition

Commonly Associated Conditions

  • NDI
    • Potassium depletion
    • Chronic hypercalcemia
    • Renal amyloidosis
    • Tubulointerstitial nephritides
    • Sjögren syndrome
    • Sickle cell anemia
    • Multiple myeloma
    • Developmental delay (in congenital NDI)
  • CDI
    • Tumors (primary and metastatic)
    • Infections (encephalitis, TB, syphilis)
    • Xanthomatosis
    • Sarcoidosis
    • Histiocytoses
    • Wolfram syndrome (DIDMOAD: DI, diabetes mellitus, optic atrophy, deafness)

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