Hypernatremia

Background

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

• Risk factor = inability to respond to thirst

Diagnosis

SYMPTOMS

>350 = begin sx

>375 = irritability, ataxia

>400 = lethargy, coma

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. Tx perfusion deficits with NS
2. Then, switch to 4.5% NS after UOP = >0.5 mL/kg/hr
3. if no UOP after rehydration, use lasix (20-40mg IV)

• Avoid lowering Na more than 10meq/L/day (chronic)!
• Around 120mL/kg/hr D5W

Water Deficit

H2O Deficit = 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)