SIADH: causes

Microbiology

The syndrome of inappropriate ADH secretion (SIADH) is characterised by hyponatraemia secondary to the dilutional effects of excessive water retention.

Causes of SIADH

Category	Examples
Malignancy	small cell lung cancer also: pancreas, prostate
Neurological	stroke subarachnoid haemorrhage subdural haemorrhage meningitis/encephalitis/abscess
Infections	tuberculosis pneumonia
Drugs	sulfonylureas* SSRIs, tricyclics carbamazepine vincristine cyclophosphamide
Other causes	positive end-expiratory pressure (PEEP) porphyrias

Management

correction must be done slowly to avoid precipitating central pontine myelinolysis
fluid restriction
demeclocycline: reduces the responsiveness of the collecting tubule cells to ADH
ADH (vasopressin) receptor antagonists have been developed

*the BNF states this has been reported with glimepiride and glipizide.