Syndrome of Inappropriate ADH
Clinical syndrome defined by a excessive secretion of ADH.
Epidemiology and Risk Factors
Pathophysiology
Causes of SIADH can be classified into:
- Primary CNS
- CVA
- Haemorrhage
- Infection
- Trauma
- TBI
- Psychosis
- Respiratory
- Pneumonia
- Aspergillus
- Tuberculosis
- Asthma
- Atelectasis
- Acute respiratory failure
- Pneumothorax
- Pneumonia
- Hormonal
- Hypothyroidism
- Hypopituitarism
- Malignancy
- Paraneoplastic syndrome
Classically small cell lung carcinoma. - Neuroblastoma
- Paraneoplastic syndrome
- Infective
- HIV
- Congenital
- Surgery
- Drugs
- Anti-convulsants
- Carbamazepine
- Sodium valproate
- Anti-depressants
- SSRIs
- MAO-Is
- TCAs
- Antipsychotics
- Haloperidol
- Analgesics
- Opioids
- NSAIDs
- Exogenous ADH
- Vasopressin
- DDAVP
- Oxytocin
- Other
- Amiodarone
- Bromocriptine
- Ciprofloxacin
- Interferon-alpha
- Interferon-gamma
- MDMA
Ecstasy.
- Anti-convulsants
- Exercise associated
- Primary polydipsia
- Idiopathic
Clinical Manifestations
Diagnostic Approach and DDx
Diagnostic criteria:
- Hypotonic hyponatraemia
- Urine osmolality > plasma osmolality
- Absence of other factors affecting ADH secretion:
- Hypotension
- Hypovolaemia
- Drugs
- Oedema
- Corrected by water restriction
Investigations
Management
- Fluid restriction
- Hypertonic saline for severe or recalcitrant cases
Avoid correction >10mmol/24 hours.
Specific therapy:
- Pharmacological
- Sodium
- Vasopressin receptor antagonists
- Fludrocortisone
- Physical
- Fluid restriction
Marginal and Ineffective Therapies
References
- Sahay M, Sahay R. Hyponatremia: A practical approach. Indian Journal of Endocrinology and Metabolism. 2014;18(6):760-771. doi:10.4103/2230-8210.141320.