A 65-year-old woman presents to the emergency department with acute confusion. Laboratory investigations reveal Her serum calcium level is 15 mg/ dL (normal range 8.5–10.5 mg/dL). creatinine clearance of 45 mL/min. Further testing shows an elevated level of 1,25-dihydroxycholecalciferol. Which of the following is the most appropriate initial management?