SIADH

 

 

 

Considerations

 

  • Hyponatremia:

    • ​Cerebral edema

    • ​Seizures

    • Coma

    • Respiratory arrest

  • Associated conditions:

    • Tumours (lung, pancreas, prostate, lymphoma)

    • CNS insult (trauma, subarachnoid hemorrhage, tumour, infection)

    • Pulmonary (infection, cystic fibrosis, positive pressure ventilation)

    • Medications (opiates, oxytocin, chlorpropamide, vincristine)

    • Postoperative ADH secretion 

    • Idiopathic

    • Iatrogenic (hypotonic IV solutions)

 

 

Treatment

 

  • Free water restriction

  • Eliminate underlying cause

  • Caution with rapid correction of serum sodium (central pontine myelinolysis)

 

 

Goals

 

  • Preoperative correction of serum electrolytes when possible to target sodium >125

  • Avoid overcorrection or overly rapid correction resulting in central pontine myelinolysis

  • Correct underlying reversible etiologies (infection, tumour, medications, iatrogenic)


 

Management

 

  • Restore sodium concentration

  • Generally restrict free water (500mL-1L/day) 

  • +/- loop diuretic 

  • Acute:

    • Severe hyponatremia (<120mEq/L or neuro symptoms)

      • Hypertonic saline 3% 1-2 ml/kg/hr until sodium >125

      • Furosemide

      • Sodium bicarbonate (1 mEq/ml) to terminate seizures: 0.5-1mL/kg boluses prn

  • Chronic:

    • Avoid rapid overcorrection (0.5-1 mEq/hr, <8 in mEq in 24hrs)

    • Demeclocycline 300-600 mg PO bid (antagonizes ADH at collecting duct)

    • Conivaptan = vasopressin receptor antagonist