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Cerebral salt-wasting syndrome (CSWS)

  1. Hyponatremia dehydration
  2. Due to hypersecretion of ANP, seen in mainly in CNS condition. In response to trauma/injury or the presence of tumors in or surrounding the brain.
  3. This form of hyponatremia is due to excessive renal sodium excretion resulting from a centrally mediated process.


  1. Polyuria due to inadequate sodium retention in the body,
  2. Polydipsia due to polyuria,
  3. Extreme salt cravings,
  4. Dysautonomia,
  5. Dehydration.
  6. Patients often "self-medicate" by naturally gravitating toward a high-sodium diet and by dramatically increasing their water intake.
  7. Advanced symptoms include muscle cramps, lightheadedness, dizziness or vertigo, feelings of anxiety or panic, tachycardia or bradycardia , hypotension and orthostatic hypotension sometimes resulting in syncope.
  8. Symptoms associated with dysautonomia include: headaches, pallor, malaise, facial flushing, constipation or diarrhea, nausea, visual disturbances, numbness, loss of consciousness and seizures.

Causes and Diagnosis

  1. CSWS is usually caused by brain injury/trauma or cerebral lesion, tumor, or hematoma.
  2. CSWS is a diagnosis of exclusion and may be difficult to distinguish from the SIADH, which develops under similar circumstances and also presents with hyponatremia. The main clinical difference is that of total fluid status of the patient:
  3. CSWS leads to a relative or overt hypovolemia whereas SIADH is consistent with a normal to hypervolemic range.
  4. Random urine sodium concentrations tend to be more than 150 mEq/L in CSWS and in (SIADH >100).
  5. If blood-sodium levels increase when fluids are restricted, SIADH is more likely.


  1. While CSWS usually appears within the first week after brain injury and spontaneously resolves in 2–4 weeks,
  2. It can sometimes last for months or years.
    While fluid restriction is used to treat SIADH, CSWS requires aggressive hydration and correction of the low sodium levels using sodium chloride tablets. (volume for volume) (Ref. Nelson. 18th ed., Pg- 2302)
  3. Sometimes, fludrocortisone (a mineralocorticoid) improves the hyponatremia.
Differences between SIADH and CSWS
S Na
Urine Na
Urine output Normal or slight
I/V fluid status
S uric acid
Treatment Restrict water ↑ Salt intake
Extra Edge

Normal serum osmolality 500 – 800 mosmol/kg


Normal urine sodium 100 – 260 meq/day or >20 meq /l (Ref. Hari. 18th ed., Pg- 3603)

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