A client is being treated for syndrome of inappropriate antidiuretic hormone (SIADH). On examination, the client has a weight gain of 4.4 lbs (2 kg) in 24 hours and an elevated blood pressure. Which intervention should the nurse implement first?

A. Serum creatinine levels are important for assessing kidney function, but the priority is to assess for signs of fluid retention, which could lead to complications. B. Diuretics (e.g., furosemide) help remove excess water, reducing fluid overload and preventing complications like pulmonary edema or severe hypertension. This directly addresses the client’s current priority problem: fluid retention and elevated BP. C. Monitoring sodium intake is important but does not immediately address the current signs of fluid retention. D. This only assesses for edema but does not treat or prevent worsening overload. Action is needed now, not just monitoring.