Hyponatremia

Management

1. Labs
   • Serum:
     • Electrolytes q1h x6h
     • Osmolality q2h x 6h
     • LFT
     • Serum Uric acid (diuretics)
     • TSH
     • Cortisol (endocrine)
   • Urine:
     • Analysis, Lytes, Urea, Uric Acid (diuretics), Osm, Creat
2. Treat CNS dysfunction
   • AMS, seizing, neuro findings
     • 3% saline 100mL IV over 10mins (or 2mL/kg), raises Na ~2mmol/L
     • May repeat once (Want more? Repeat Na prior to correction)
   • Consider Head CT if still wonky
3. Hang tight (avoid osmotic demyelination)
   • Fluid restrict, Foley, Fall precautions and Admit (no more fluids!)
     • Rule of 6’s: Six-a-day for safety (6mEq/L x 24h), Six in six hours for severe symptoms then stop (seizure, AMS)
       • Note: Care when replacing potassium as it will raise Na
     • Only give some NS if truly hypotensive
   • If overcorrected → dDAVP 2mcg IV/sc x1, D5W 6mL/kg over one hour and consult renal

DDx

• Euvolemia
  • SIADH, stress
  • Drug: Thiazide diuretics, Ecstasy, SSRI
  • Endocrine: Hypothyroid, Adrenal insufficiency
  • Exercise-induced (Marathon)
  • Cerebral salt-wasting (subarachnoid)
• Hypervolemia
  • Renal failure
  • Cardiac failure
  • Cirrhosis
  • Primary polydipsia, beer potomania, tea-toast diet
• Hypovolemia (Renal vs. Extrarenal)