Cerebral Salt Wasting

  • inappropriate sodium wasting in the urine in the setting of acute disease in central nervous system (CNS), usually subarachnoid hemorrhage
  • less common cause of hyponatremia than SIADH

CSW

Pathophysiology: 

  1. release of BNP [brain natriuretic peptide] / diminished CNS sympathetic activity –>
  2. impaired Na reabsorption –>
  3. volume depletion, inc ADH release, hyponatremia, inc neurologic injury

Lab Findings

  1. low Na
  2. low serum osm
  3. high urine osm [inappropriate] [>100 mosm/Kg; usually >300]
  4. low serum uric acid [urate wasting in urine]

Treatment:  In patients with a clinical picture compatible with CSW, treatment should begin with isotonic saline to correct the volume depletion and possibly reverse the hyponatremia

Capture

  1. Patients with severe symptoms should be treated in the ICU with hypertonic saline and fludrocortisone.
  2. Acute hyponatremia and/or severe symptoms should have 6 mmol/L corrected over 6 h or until severe symptoms improve.
  3. The total correction of Na should not exceed 8 mmol/L over 24 h. Therefore, if 6 mmol/L is corrected in 6 h, the Na should not be increased more than 2 mmol/L in the following 18 h.
  4. The total correction of Na is based on the Na deficit which is calculated  conservatively with the formula depicted.
  5. With improvement of symptoms, the patients can be moved to the less aggressive treatments in the algorithm, until Na reaches 131 mmol/L.
  6. SAH patients are an exception and receive treatment even for a serum Na of 131–135 mmol/L.

*HHH hypervolemia, hypertension, hemodilution (NOT RECOMMENDED ANYMORE); IMC intermediate care unit, U urine,

 

References

Uptodate.com,. “Cerebral Salt Wasting”. N.p., 2015. Web. 14 Dec. 2015.

Layon, A. Joseph, Andrea Gabrielli, and William A Friedman. Textbook Of Neurointensive Care. Print.

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