Creating 0.45% Saline for Hypernatremia Treatment in Children
Critical Warning: Do NOT Use 0.45% Saline for Hypernatremia
0.45% saline should NOT be used to treat hypernatremia in children—this would worsen the condition. Hypernatremia requires hypotonic fluids (lower sodium concentration than blood), while 0.45% saline is still hypertonic relative to the patient's needs and will exacerbate sodium elevation 1.
Correct Fluid Choice for Hypernatremia
Use 5% dextrose in water (D5W) as the primary rehydration fluid for hypernatremic children. This provides free water without additional sodium load 1, 2.
Why Avoid Saline Solutions
- Normal saline (0.9% NaCl) has tonicity of
300 mOsm/kg H₂O, which is 3-fold higher than typical urine osmolality in conditions causing hypernatremia (100 mOsm/kg H₂O) 1 - Approximately 3 liters of urine are needed to excrete the renal osmotic load from 1 liter of isotonic fluid, risking serious worsening of hypernatremia 1
- Salt-containing solutions should be avoided because of their large renal osmotic load 1
Proper Treatment Protocol for Hypernatremia
Initial Fluid Administration
Calculate initial fluid rate based on physiological maintenance requirements:
- First 10 kg: 100 ml/kg/24h
- 10-20 kg: add 50 ml/kg/24h
- Remaining weight: add 20 ml/kg/24h
- Adults: 25-30 ml/kg/24h 1, 2
Correction Rate Guidelines
Target sodium reduction of 0.5 mmol/L per hour or 10-15 mmol/L per 24 hours maximum 2, 3. While recent evidence suggests faster correction may be safe, guidelines recommend cautious approach to avoid cerebral edema 3, 4.
Monitoring Requirements
- Check serum sodium every 2-4 hours initially during active correction 2
- Monitor for signs of cerebral edema: altered mental status, seizures, headache 2, 4
- Track daily weights and fluid balance 2
- Aim for normalization within 48-72 hours 2, 5
When 0.45% Saline IS Appropriate (Different Context)
0.45% saline is used for diabetic ketoacidosis (DKA) maintenance after initial resuscitation, NOT for hypernatremia treatment 1. In DKA, once glucose reaches 250 mg/dl, fluids are changed to 5% dextrose with 0.45-0.75% NaCl 1.
Common Pitfalls to Avoid
- Never use normal saline or any saline solution as primary rehydration fluid in hypernatremia—this worsens the condition 1, 2
- Failing to monitor electrolytes frequently during correction can lead to complications 2
- Correcting too rapidly (>0.5 mmol/L/hour) may increase risk of cerebral edema, though recent data questions this 3, 4
- Inadequate calculation of ongoing losses leads to insufficient rehydration 2