Syndrome of inappropriate antidiuretic hormone secretion

Keywords: SIADH


Appropriate Tests


Syndrome of inappropriate antidiuretic hormone secretion: characterised by hyponatraemia, with Sodium urine >20 mmol/L and Osmolality urine > Osmolality (plasma).

Osmolality and Osmolality urine; Sodium and Sodium urine; levels of Creatinine, Urea and Urate tend to be low in SIADH, but high in patients in whom Hyponatraemia is associated with hypovolaemia.

Hypothyroidism, Addison’s disease and diuretic therapy must be excluded on clinical or pathological findings.

See also Hyponatraemia

  • Carcinoma, especially
    • Lung
    • Pancreas
  • Lymphoma (non-Hodgkin)


Respiratory disorders
  • Pneumonia
  • Tuberculosis
  • Lung abscess


Neurological disorders
  • Head injury
  • Subdural haematoma
  • Cerebral infarction
  • Subarachnoid haemorrhage
  • Encephalitis
  • Post-craniotomy


Drug effects
  • Chlorpropamide
  • Vincristine
  • Vinblastine
  • Cyclophosphamide
  • Carbamazepine
  • Narcotics
  • Tricyclic antidepressants


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