Hypernatremia

Background

• High = >150meq/L
• High! = (Osm >350)

Clinical Presentation

Na	Symptoms
350-375	Restlessness, irritability
>375-400	Tremulousness, ataxia
400-430	Hyperreflexia, twitching, spasticity
>430	Seizure, coma, death

Causes of Hypernatremia

Usually secondary to decreased Total Body Water

• Water loss
  • Decreased Intake
  • Water loss > Na loss
    • Vomiting
    • Diarrhea
    • Sweating
    • Dialysis
    • Osmotic diuresis
    • Central DI
      • Head Trauma
      • CVA
      • Tumor
      • Infect
    • Nephrogenic DI
    • Thyroidtoxicosis
• Na gain
  • Increased intake
    • Na intake
    • NaBicarb
  • Renal Na retention (secondary to poor perfusion)

Diagnosis

Treatment

• NS until perfusion deficits corrected
  • Then switch to 1/2NS until UOP = >0.5 mL/kg/hr

• Avoid lowering Na more than 10-15meq/L/day

• Central DI --> Tx with DDAVP
• Peds: >180meq/L consider peritoneal dialysis

Water Deficit

• Free water deficit = (0.6 x wt in kg) x [(serum Na/140) – 1]

• Each liter H2O Deficit increases Na by 3-5 meq/L

See Also

• Electrolyte Abnormalities (Main)
• MDCalc: www.mdcalc.com/free-water-deficit-in-hypernatremia