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?

A. Restrict fluid intake to 1,000 mL per day. SIADH involves excessive release of antidiuretic hormone, leading to water retention and dilutional hyponatremia. Fluid restriction is the primary intervention to prevent further expansion of intravascular volume and allow serum sodium levels to rise. Restricting intake to 1000 mL or less addresses the underlying pathophysiology of water intoxication in these clients. B. Provide a diet containing 2 g of sodium per day. A 2 g sodium limit is a restricted diet typically used for heart failure or hypertension to prevent fluid retention. In SIADH, the client needs increased sodium intake or salt tabs to correct the severe deficit of 123 mEq/L. Lowering sodium intake would worsen the hyponatremia and increase the risk of cerebral edema and seizures. C. Administer desmopressin acetate 0.2 mg orally. Desmopressin is a synthetic form of antidiuretic hormone used to treat diabetes insipidus, which is the opposite of SIADH. Giving this medication would cause even more water retention and further lower the serum sodium level. This would be life-threatening for a client who already has excessive ADH activity and critical hyponatremia. D. Maintain an IV of 0.45% sodium chloride. Half-normal saline is a hypotonic solution that would provide more free water than solute to the patient. This would exacerbate the dilutional hyponatremia and increase the risk of life-threatening brain swelling. If intravenous fluids are required for SIADH with severe symptoms, hypertonic saline (3% NaCl) is used with extreme caution.