HYPERNATREMIA

November 22, 2014
    • HPI: A 6-month-old male infant with watery diarrhea at home for the past 5 days and vomiting for 1 day presents with intermittent lethargy and irritability.
      • He has also not had any wet diapers for the past 24 hours.
      • He has nursed poorly.
    • PE
      • Vital signs are temperature 102°F, respiratory rate 40 breaths/min, O2 saturation 95%, and heart rate 190 beats/min.
      • He is crying without tears.
      • He has increased muscle tone in all extremities
        Hypernatremia most commonly presents with jitteriness (which can be mistaken for seizures) and lethargy.
        Findings of dehydration may be lessened relative to the degree of dehydration because of relative preservation of extracellular fluid.
        Hypernatremia is defined as a serum sodium >150 mEq/L.
        The causes of excess water loss resulting in hypernatremia include:
        • Insensible losses
        • Gastrointestinal (GI) loss: infectious diarrhea (rotavirus). Fecal losses contain more water than sodium (fecal analysis: 35–60 mEq Na/L).
        • Less commonly renal concentrating defects: obstructive uropathy and diabetes insipidus (DI)
          Using skimmed cow’s milk (high solute), either boiled or nonboiled, to treat diarrhea of infancy has been shown to result in hypernatremic dehydration
      • Phase I
        • Replace water orally or intravenously.
        • If treating intravenously, begin with isotonic saline to restore systemic perfusion. Use 20 mL/kg over 30 minutes repeatedly until hypovolemia is corrected. (There may be an initial elevation in sodium of 5–8 mEq/L after initial treatment because of a physiologic adjustment period. No intervention should be performed in response to this transient elevation.)
        • The targeted rate of lowering the plasma sodium is 12–15 mEq/L/day. (Fluid administration rates will be lower than with isotonic dehydration to avoid complications.)
      • Phase II
        • Begin IV fluids of 5% dextrose quarter normal (40 mEq/L sodium) solution at 2–2.5 L/m2/day.
        • Measure sodium serum every 4–6 hours. If correction is too slow, increase the rate of IV fluids. If correction is too fast, decrease the rate of IV fluids.
    • CASE:Therapy
      • Phase I
        • During placement of an IV line, a set of electrolytes is obtained.
        • After administration of an isotonic saline bolus at 20 mL/kg, the initial serum sodium returns as 185 mEq/L. Another saline bolus of 20 mL/kg is given to complete the restoration of perfusion.
      • Phase II
        • D51/4NS + 20 mEq/L KCl was then started at 2 L/m2/day.

About Dr. Jayaprakash

Asst. Prof. of Pediatrics, ICH. Institute of Child Health. Gov. Medical College Kottayam. Kerala, India.

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