21st May 2025

Aetiology

The causes of SIADH are various. A useful mnemonic for remembering these causes is, “SIADH” 

Surgery – pituitary/ neurosurgery

Intracranial – head injury, intracranial infections, stroke, pituitary apoplexy, hypopituitarism

Alveolar causes – small cell lung cancer

Drugs – thiazide diuretics, cyclophosphamide, TCAs, carbamazepine, SSRIs, opioids

Hormonal – low cortisol, hypothyroidism, Addison’s disease 

Other causes include HIV infection, Guillain-Barre syndrome, multiple sclerosis, tuberculosis, pneumonia (particularly if caused by legionella or mycoplasma)