Nephrology

Answer 3 IV hypertonic saline (3%) at 130 mL/hr. This patient is exhibiting severe neurologic manifestations of hyponatremia, and the appropriate treatment is to raise serum tonicity. The goal rate of correction in such serious cases is generally 1.5 to 2 mEq/L/hr for the first 3 to 4 hours or until symptoms have resolved.2 TBW is a fraction of body weight (0.5 L/kg for younger women and older men, 0.6 L/kg for younger men, and 0.45 L/kg for older women), and infusate sodium varies with the type of fluid chosen (513 mEq/L for 3% saline; 154 mEq/L for 0.9% saline). When neurologic symptoms continue, 3% saline can be used to provide more rapid correction. Given that this patient is symptomatic, serum sodium should be raised by 6 mEq/L rapidly over 3 hours or until neurologic symptoms resolve. To increase the serum sodium from 110 mEq/L to 116 mEq/L in a 70-kg woman (35 L TBW), 210 mEq/L of sodium or approximately 400 mL of 3% saline is required. This should be given over 3 hours or at a rate of 130 mL/hr to raise the serum sodium concentration by no more than 2 mEq/L/hr. REFERENCE 2. Douglas I. Hyponatremia: why it matters, how it presents, and how we can manage it. Clev Clin J Med 2006;73 Suppl 3:S4-12. Click here to return to the questions

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