Syndrome of inappropriate ADH

Background

Etiologies

• CNS: stroke, intracranial hemorrhage, infection, trauma, and psychosis
• Malignancy: ectopic ADH production by small cell carcinoma or, even more rarely, with other lung cancers, head-and-neck cancer, olfactory neuroblastoma, and extrapulmonary small cell carcinoma
• Medications: chlorpropamide, carbamazepine, oxcarbazepine, high-dose cyclophosphamide, SSRIs
  • Others: vincristine, cinblastine, cinorelbine, cisplatin, thiothixene, thioridazine, haloperidol, amitriptyline, MAO inhibitors, melphalan, ifosfamide, methotrexate, opiates, NSAIDs, interferon alpha, interferon gamma, sodium valproate, bromocriptine, lorcainide, amiodarone, ciprofloxacin, high-dose imatinib, and ecstasy
• Surgery, likely mediated by pain, but also specifically after transsphenoidal pituitary surgery
• Lung disease: pneumonia, occasionally also with asthma, atelectasis, respiratory failure, and pneumothorax
• Endocrinopathies: hypopituitarism and hypothyroidism
  • Also exogenous vasopressin, desmopressin, and oxytocin
• HIV
• Hereditary SIADH
• Idiopathy, more common in older patients though occasionally found later to be from occult malignancy

Differential Diagnosis

• Cerebral salt wasting, which mimics SIADH and is most commonly caused by subarachnoid hemorrhage