Management of Hypernatremia (Sodium 152.2 mmol/L)
For a sodium level of 152.2 mmol/L, you should initiate controlled correction with hypotonic fluids, aiming to reduce sodium by no more than 8-10 mmol/L per 24 hours to prevent cerebral edema, while simultaneously identifying and treating the underlying cause. 1, 2
Initial Assessment
Determine the acuity and volume status immediately:
- Acute vs. chronic hypernatremia: If onset is <24-48 hours, more rapid correction is safer; if >48 hours (chronic), slow correction is mandatory to prevent osmotic demyelination 2, 3
- Volume status evaluation: Check for signs of hypovolemia (orthostatic hypotension, dry mucous membranes, decreased skin turgor), euvolemia, or hypervolemia (edema, jugular venous distension) 2, 4
- Measure urine osmolality and sodium: Urine osmolality >800 mOsm/kg suggests extrarenal water loss; <300 mOsm/kg suggests diabetes insipidus 2, 4
- Check urine volume: Polyuria (>3 L/day) points toward diabetes insipidus 4
Correction Strategy
Calculate the water deficit using the formula:
Correction rate guidelines:
- For chronic hypernatremia (>48 hours): Reduce sodium by no more than 0.4 mmol/L/hour or 8-10 mmol/L per 24 hours to prevent cerebral edema 2, 3
- For acute hypernatremia (<24 hours): More rapid correction is acceptable, but still monitor closely 2, 3
- Monitor sodium levels every 2-4 hours initially, then adjust frequency based on response 1, 4
Fluid Selection and Administration
Choose hypotonic fluids for correction:
- 0.45% NaCl (half-normal saline) containing 77 mEq/L sodium is appropriate for moderate hypernatremia 5
- 0.18% NaCl (quarter-normal saline) containing 31 mEq/L sodium provides more aggressive free water replacement 5
- D5W (5% dextrose in water) can be used for pure free water replacement in severe cases 5
- Avoid isotonic fluids (0.9% NaCl) as they will worsen hypernatremia 5
Infusion approach:
- Replace calculated water deficit over 48-72 hours for chronic hypernatremia 4
- Add ongoing losses (insensible losses ~500-1000 mL/day plus any measured losses) 4
- Adjust infusion rate based on frequent sodium monitoring 1, 4
Treatment Based on Underlying Cause
For hypovolemic hypernatremia (extrarenal losses):
- Begin with hypotonic saline (0.45% NaCl) to restore volume while correcting sodium 1, 2
- Address underlying cause (diarrhea, vomiting, burns) 2
For euvolemic hypernatremia (diabetes insipidus):
- Central diabetes insipidus: Administer desmopressin (Minirin) alongside hypotonic fluids 2, 3
- Nephrogenic diabetes insipidus: Treat underlying cause (discontinue lithium, correct hypokalemia); hypotonic fluid replacement is primary therapy 2, 4
For hypervolemic hypernatremia (sodium excess):
- Consider hemodialysis for acute severe cases, especially if sodium >160 mmol/L 3
- Use loop diuretics with hypotonic fluid replacement 2
Critical Safety Considerations
Common pitfalls to avoid:
- Never correct chronic hypernatremia faster than 8-10 mmol/L per 24 hours - this risks cerebral edema and seizures 2, 3
- Do not use normal saline (0.9% NaCl) - it will exacerbate hypernatremia 5
- Inadequate monitoring during correction can lead to overcorrection or undercorrection 1, 4
- Failing to account for ongoing losses (insensible, urinary) will result in inadequate correction 4
Monitoring Protocol
Laboratory monitoring schedule:
- Check sodium every 2 hours during initial correction phase 1, 4
- Once stable, check every 4-6 hours 4
- Monitor for neurological changes (confusion, seizures, altered consciousness) 1, 2
- Track fluid balance meticulously (input/output) 4
Special Populations
In patients with renal concentrating defects (nephrogenic diabetes insipidus):
- Require ongoing hypotonic fluid administration to match excessive free water losses 5
- Isotonic fluids are contraindicated as they worsen hypernatremia 5
For severe hypernatremia (>160 mmol/L) with acute onset: