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  • • Water deficit without solute deficit

    • Rare in surgical patients

    • Water deficit can be estimated from serum Na concentration

    • Water deficit: ((140 - serum Na) * total body water))/140




  • • Occurs in patients unable to regulate water intake

    • Insensible water loss from fever

    • Tube feedings with inadequate water content

    • Diabetes insipidus


Symptoms and Signs


  • • Concentrated urine

    • CNS depression

    • Lethargy

    • Coma

    • Muscle rigidity

    • Tremors

    • Spasticity

    • Seizures


Laboratory Findings


  • • Hypernatremia

    • Low urine Na despite hypernatremia


  • • Water deficit usually accompanied by solute (Na+) deficit


  • • Physical exam

    • Serial serum Na


  • • Replacement of enough water to return serum Na concentration to normal

    • Treat patient with D5W unless hypotension has developed in which case hypotonic saline should be used


Treatment Monitoring


  • • Serum Na




  • • Excellent




  • • Adequate water intake



Palevsky PM et al. Hypernatremia in hospitalized patients. Ann Intern Med. 1996;124:197.  [PubMed: 8533994]
Body JJ. Current and future directions in medical therapy: hypercalcemia. Cancer. 2000;88(12 Suppl):3054.

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