Syndrome of inappropriate antidiuretic hormone secretion
Syndrome of inappropriate antidiuretic hormone secretion (SIADH or SIAD) was described in patients with lung cancer who developed hyponatraemia associated with continued urinary sodium loss. The result is often dilutional hyponatremia in which the sodium remains normal but total body fluid increases.
Inappropriate (excessive) release of antidiuretic hormone (ADH), later discovered to consist of arginine-vasopressin (AVP), may be caused by:
- malignant tumours, in particular: head and neck cancer, non-small cell lung cancer, small cell lung cancer (representing a paraneoplastic syndrome)
- positive pressure ventilation
- conditions with decreased left atrial pressure
- pharmaceutical agents
Treatment and prognosis
The optimal therapy for SIADH is to treat the underlying cause. If this is not possible, or if the disease has become refractory, other treatment methods are available such as water restriction, demeclocycline therapy, or in severe cases infusion of hypertonic saline together with frusemide during careful monitoring.
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- 3. Zietse R, van der Lubbe N, Hoorn EJ. Current and future treatment options in SIADH. NDT Plus. 2009;2 (suppl 3): iii12-iii19. doi:10.1093/ndtplus/sfp154 - Free text at pubmed - Pubmed citation