Treatment of Central Salt Wasting
The treatment of central salt wasting (CSW) requires aggressive volume repletion with isotonic saline, sodium replacement with hypertonic saline for severe cases, and fludrocortisone as a first-line pharmacological intervention to reduce ongoing natriuresis. 1
Diagnosis and Differentiation from SIADH
Proper treatment begins with accurate diagnosis, as CSW is often confused with SIADH:
Key diagnostic features of CSW:
- Hypovolemia (vs. euvolemia in SIADH)
- Hyponatremia
- Elevated urine osmolality
- Elevated urine sodium
- Inappropriate natriuresis despite hypovolemia
Laboratory assessment:
- Serum sodium < 131 mmol/L
- Assessment of volume status
- Measurement of serum and urine osmolality
- Urine sodium concentration
Treatment Algorithm
1. Volume Repletion
- First step: Isotonic saline (0.9% NaCl) for volume expansion 1
- Monitoring: Check serum sodium every 4-6 hours
- Goal: Restore intravascular volume to prevent cerebral ischemia
2. Sodium Replacement Based on Symptom Severity
For severe symptoms (seizures, altered mental status, coma):
- Administer 3% hypertonic saline to increase serum sodium by 4-6 mEq/L in first 1-2 hours
- Transfer to ICU for close monitoring
- Calculate sodium deficit using: Desired increase in Na (mEq) × (0.5 × ideal body weight)
For moderate symptoms (nausea, vomiting, headache):
- Use isotonic saline (0.9% NaCl) for volume expansion
- Consider 3% hypertonic saline if symptoms worsen
For mild/no symptoms:
- Use isotonic saline for volume repletion
3. Pharmacological Management
Fludrocortisone (first-line):
- Starting dose: 50-100 μg/day
- May increase to 150-200 μg/day if needed
- Strong evidence (Class I) supports its use to reduce ongoing natriuresis 1
Hydrocortisone (alternative):
- Dose: 50-100 μg/day
- Particularly useful in patients with subarachnoid hemorrhage 1
Monitoring and Maintenance
- Correction rate: No more than 8 mmol/L per 24 hours to avoid osmotic demyelination syndrome
- High-risk patients (alcoholism, malnutrition, liver disease): Lower correction rate of 4-6 mEq/L per day
- Regular monitoring:
- Volume status assessment
- Blood pressure
- Serum potassium
- Daily weight
- Intake and output
Important Considerations and Pitfalls
- Avoid fluid restriction: Even with mild hyponatremia, fluid restriction can worsen hypovolemia and cerebral ischemia 1
- Duration of treatment: Continue until the underlying neurological condition resolves, with gradual tapering of medications while monitoring sodium levels
- Misdiagnosis risk: Treating CSW as SIADH can lead to worsening hypovolemia and cerebral ischemia 1
- Aggressive approach: CSW often requires substantial volumes of hypertonic saline for a prolonged period 2
Evidence from Clinical Experience
Case reports demonstrate that patients with CSW may require large doses of hypertonic saline, with substantial benefit from the addition of fludrocortisone 2. In some cases, fludrocortisone doses of 0.1 mg three times daily have been necessary to control severe natriuresis 3.
The American Heart Association guidelines acknowledge that aggressive volume resuscitation can ameliorate the effect of cerebral salt wasting on the risk of cerebral ischemia after subarachnoid hemorrhage, and that 3% saline solution is effective in correcting hyponatremia in this setting 4.