A client who has small cell carcinoma of the lung is admitted with symptoms of syndrome of inappropriate antidiuretic hormone (SIADH). As the client responds to treatment, the client's serum sodium level increases from 120 mEq/L (120 mmol/L) to 125 mEq/L (125 mmol/L). Based on this finding, which intervention should the nurse implement?Reference Range:Sodium [136 to 145 mEq/L (136 to 145 mmol/L)]