Hypernatremia

Background

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

• Risk factor = inability to respond to thirst

Diagnosis

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

DDX

1. H2O loss
   1. Decreased Intake
   2. H2O loss > Na loss
      1. vomit
      2. diarrhea
      3. sweating
      4. dialysis,
      5. osmotic diuresis
      6. Central DI
         1. Head trauma
         2. CVA
         3. Tumor
         4. Infect
      7. Nephrogenic DI
      8. Thyroidtoxicosis
2. Na gain
   1. Increased Intake
      1. Na intake
      2. NaBicarb
   2. Renal Na retention
      1. (2nd poor perfusion)

Treatment

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

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

Water Deficit

H2O Deficit (L) = TBW (1 - (measured Na/desired Na))

• Each liter H2O Deficit increases measured Na by 3-5 meq/L
• Central DI --> Tx with DDAVP
• In Peds >180meq/L consider peritoneal dialysis

See Also

MDCalc: www.mdcalc.com/free-water-deficit-in-hypernatremia

Source

2/4/06 DONALDSON (adapted from Tintinalli)