Rapid Correction of Hypernatremia After Fluid Restriction
Immediate Fluid Management
For hypernatremia (Na 153 mEq/L) requiring rapid correction after fluid restriction, infuse hypotonic fluids—specifically 0.45% NaCl (half-normal saline) or D5W (5% dextrose in water)—with the choice depending on volume status and clinical context. 1
Primary Hypotonic Fluid Options
0.45% NaCl (half-normal saline) contains 77 mEq/L sodium with osmolarity ~154 mOsm/L, making it appropriate for moderate hypernatremia correction while providing both free water and some sodium replacement 1
D5W (5% dextrose in water) provides pure free water replacement and is recommended when more aggressive free water repletion is needed, particularly in patients with significant volume overload or those requiring concurrent renal replacement therapy 1, 2
0.18% NaCl (quarter-normal saline) contains ~31 mEq/L sodium and may be used for more aggressive free water replacement in severe hypernatremia 1
Critical Correction Rate Guidelines
The correction rate must not exceed 8-10 mmol/L per 24 hours for chronic hypernatremia (>48 hours duration) to prevent osmotic demyelination syndrome. 1, 3
For acute hypernatremia (<24-48 hours), more rapid correction may be tolerated, but close monitoring remains essential 3, 4
Reduce sodium at a rate of 10-15 mmol/L per 24 hours maximum, with correction occurring over 48-72 hours for severe cases 1, 5
Special Clinical Scenarios
Patients with Renal Concentrating Defects
Patients with nephrogenic diabetes insipidus or significant renal concentrating defects require ongoing hypotonic fluid administration to match excessive free water losses 1
Avoid isotonic fluids (0.9% NaCl) in these patients, as this will worsen hypernatremia 1
Patients on Continuous Renal Replacement Therapy (CRRT)
When CRRT is required, use calculated amounts of D5W prefilter (pre-blood pump) to prevent overcorrection while maintaining recommended effluent volumes of 20-25 mL/kg/hr 2, 6
Standard isotonic replacement fluids in CRRT can cause rapid overcorrection; D5W dilution of dialysate/replacement solutions allows gradual, controlled correction 2, 6
Acute Sodium Overload Cases
For rapid-onset hypernatremia from sodium overload, individualized rapid infusion of dextrose-based hypotonic solutions is the primary treatment 4
Target Na ≤160 mEq/L within 8 hours, Na ≤150 mEq/L within 24 hours, and Na ≤145 mEq/L within 48 hours for successful outcomes 4
Hemodialysis may be considered for acute hypernatremia (<24 hours) to rapidly normalize sodium levels 3
Volume Status Considerations
If hypovolemic: Use 0.45% NaCl to provide both volume repletion and free water 1
If euvolemic or hypervolemic: Use D5W for pure free water replacement without additional sodium load 1, 2
Assess for signs of volume depletion (orthostatic hypotension, dry mucous membranes, decreased skin turgor) versus volume overload (edema, jugular venous distention) 1
Monitoring Requirements
Check serum sodium every 2-4 hours during active correction phase 1, 3
Monitor for treatment-related hyperglycemia when using dextrose-based solutions 4
Watch for signs of cerebral edema if correction is too rapid (confusion, seizures, altered mental status) 3, 5
Adjust infusion rates to maintain target correction speed and avoid exceeding 8-10 mmol/L per 24 hours 1, 3
Common Pitfalls to Avoid
Never use isotonic saline (0.9% NaCl) for hypernatremia correction—this will exacerbate the problem in patients unable to excrete free water appropriately 1
Avoid correcting chronic hypernatremia faster than 48-72 hours, as this increases risk of osmotic demyelination syndrome 3, 5
Do not start renal replacement therapy without considering the risk of rapid sodium drops in patients with chronic hypernatremia 3
In salt intoxication cases, diuretics must be given in addition to slow water replacement to prevent pulmonary edema 5