Cerebral salt wasting syndrome
The etiology and incidence of salt wasting due to central nervous system injury is not known. It is a rare cause of hyponatremia and has likely decreased in incidence due to early delivery of isotonic saline in patients with subarachnoid hemorrhage.
Clinically, patients develop hypotension, hemoconcentrated blood cell lines (elevated hemoglobin, platelets, and perhaps WBC count), and high urine output. Symptoms typically manifest within 10 days of cerebral injury. Hyponatremia is a serologic marker paramount to establishing the diagnosis.
If appropriately treated, CSW should resolve fully within a few weeks of diagnosis, and no long-term follow-up is warranted.
E87.1 – Hypo-osmolality and hyponatremia
89627008 – Hyponatremia
Differential Diagnosis & Pitfalls
- Pseudohyponatremia (see hyponatremia)
- SIADH – has numerous causes
- Glucocorticoid deficiency
- Nephrogenic SIADH
- Exercise-associated hyponatremia
- Polydipsia due to psychosis
- Low dietary solute intake
- Chronic kidney disease
- Medication-induced hyponatremia – typically secondary to diuretics such as thiazides
- Congestive heart failure
- Volume depletion (hypovolemic hyponatremia)
- Reset osmostat – due to pregnancy, genetic causes, chronic disease