What is the most appropriate means of correcting this patient's hyponatremia?

Question

Quizplus · Accepted Answer

Explanation: The hyponatremia that arises in SIADH is secondary to the combination of water retention and the loss of sodium and potassium. In chronic SIADH, the loss of sodium is more significant than the amount of water retained. Unless there are neurologic symptoms arising from the hyponatremia, it should be corrected slowly with water restriction (Choice A). Once water restriction is initiated, the plasma sodium concentration will slowly begin to normalize. An ideal rate of increase is 0.5 mEq/h. Patients must be simultaneously monitored for volume depletion as a sodium deficit may become apparent, requiring concomitant administration of salt. Demeclocycline (Choice B) and lithium (Choice E) work to blunt the response of the collecting tubule cells to ADH, ultimately increasing the excretion of water. These drugs are indicated in patients with persistent severe hyponatremia when water restriction, salt intake, or loop diuretics fail to resolve the condition. Although it is potentially nephrotoxic, demeclocycline is typically preferred to lithium because it is more effective and less toxic. Furosemide (Choice C) lowers the urine osmolality and blunts renal response to ADH, thereby increasing water excretion. Since loop diuretics decrease NaCl reabsorption in the loop of Henle, they should be administered concomitantly with hypertonic saline or salt tablets. Hydrochlorothiazide (Choice D) may induce hyponatremia, typically within a few weeks of starting therapy. Thiazides cause the loss of both sodium and water, and when the water is better replaced than the sodium, hyponatremia ensues. Educational Objective: Water restriction (with the possible inclusion of salt administration) is the preferred means of correcting mild to moderate hyponatremia associated with SIADH.

What Is the Most Appropriate Means of Correcting This Patient's