A nurse is caring for a client who has syndrome of inappropriate antidiuretic hormone (SIADH) and a sodium level of 123 mEq/L. Which of the following prescriptions should the nurse anticipate?

Choice A rationale Desmopressin is a synthetic analog of antidiuretic hormone used to treat diabetes insipidus, which is the opposite of SIADH. In SIADH, there is already an excessive secretion of antidiuretic hormone, leading to water retention and dilutional hyponatremia. Administering more antidiuretic hormone would worsen the fluid overload and further decrease the sodium level below the current 123 mEq per L. This would increase the risk of cerebral edema and seizures. Choice B rationale Fluid restriction is the primary treatment for SIADH to correct dilutional hyponatremia. The client has a sodium level of 123 mEq per L, which is well below the normal range of 135 to 145 mEq per L. By limiting total fluid intake to 1,000 mL per day or less, the body is forced to eliminate excess water, which helps to gradually increase the serum sodium concentration. This prevents further expansion of the extracellular fluid volume. Choice C rationale A diet limited to 2 grams of sodium per day is a low-sodium diet often used for heart failure or hypertension. However, in SIADH, the low sodium level is caused by an excess of water rather than a deficiency of salt. While increasing salt intake might be helpful in some cases of SIADH, restricting sodium to 2 grams would be counterproductive or insufficient. The focus remains on managing the water imbalance rather than strictly limiting salt. Choice D rationale An intravenous solution of 0.45 percent sodium chloride is a hypotonic fluid. Administering hypotonic fluids to a patient with SIADH and a sodium level of 123 mEq per L is dangerous. It provides more free water, which would further dilute the serum sodium and worsen the hyponatremia. If intravenous fluids are required for a patient with severe hyponatremia, hypertonic saline like 3 percent sodium chloride is used under very careful monitoring.