Syndrome of inappropriate antidiuretic hormone secretion

Keywords: SIADH

Causes

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

Malignancy
  • 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