Treatment of Hypernatremia (Sodium 164 mEq/L)
For a sodium level of 164 mEq/L, administer hypotonic fluids (0.45% NaCl or D5W) to correct the free water deficit, with a maximum reduction rate of 10-15 mmol/L per 24 hours to prevent cerebral edema. 1
Immediate Assessment
Determine the duration of hypernatremia (acute vs. chronic) through clinical history, as this dictates correction speed—acute hypernatremia (<24-48 hours) can be corrected more rapidly, while chronic hypernatremia requires slow correction to avoid cerebral edema, seizures, and neurological injury 1, 2
Assess volume status by examining for signs of hypovolemia (orthostatic hypotension, dry mucous membranes, decreased skin turgor) versus hypervolemia (edema, jugular venous distention), as this guides fluid selection 3
Identify the underlying cause through history and urine osmolality—impaired thirst mechanism, lack of water access, excessive losses (diarrhea, burns), diabetes insipidus, or iatrogenic causes are most common 1, 3
Fluid Replacement Strategy
Use hypotonic fluids as primary therapy: 0.45% NaCl (half-normal saline containing 77 mEq/L sodium) or D5W (5% dextrose in water) depending on severity and clinical context 4, 3
Avoid isotonic fluids (0.9% NaCl) in patients with hypernatremia, as normal saline will worsen the condition by providing inadequate free water 4
For severe hypernatremia with symptoms (confusion, altered consciousness, seizures), intravenous hypotonic fluid replacement is necessary rather than oral rehydration 3
Critical Correction Rate Guidelines
Maximum reduction: 10-15 mmol/L per 24 hours for chronic hypernatremia (>48 hours duration) to prevent cerebral edema 1, 2
For acute hypernatremia (<24 hours), more rapid correction is permissible, though hemodialysis may be considered for very rapid normalization if needed 2
Monitor serum sodium every 4-6 hours during active correction to avoid both undercorrection and overcorrection, both associated with poor outcomes 1
Special Populations
Neonates and very low birth weight infants require particularly careful management with slow correction rates (10-15 mmol/L/24h) and daily monitoring of weight and serum electrolytes 1
Patients with diabetes insipidus may require desmopressin (Minirin) in addition to free water replacement 2
Patients with renal concentrating defects (such as nephrogenic diabetes insipidus) require ongoing hypotonic fluid administration to match excessive free water losses 4
Common Pitfalls to Avoid
Too rapid correction of chronic hypernatremia can induce cerebral edema, seizures, and permanent neurological injury—this is the most critical error to avoid 1, 2
Starting renal replacement therapy in patients with chronic hypernatremia without adjusting dialysate composition can cause dangerously rapid sodium drops 2
Using isotonic saline in hypernatremic patients will exacerbate the condition rather than correct it 4
Inadequate monitoring frequency during correction increases risk of complications from both over- and undercorrection 1
Monitoring Parameters
Check serum sodium every 4-6 hours during active correction phase 1
Monitor for neurological symptoms: confusion, altered consciousness, seizures, or signs of cerebral edema 3, 5
Track daily weights and fluid balance to assess adequacy of free water replacement 1
Reassess volume status regularly to guide ongoing fluid management 3