A 79-year-old male patient with diabetes mellitus was given tolvaptan (15 mg orally once daily) combined with furosemide, levosimendan, and recombinant human brain natriuretic peptide for heart failure 7 years after coronary artery bypass grafting and clopidogrel, metoprolol, ezetimibe, insulin glargine, and liraglutide were given concomitantly for coronary atherosclerotic heart disease and diabetes mellitus. Three days later, his heart failure symptoms were improved, but he developed hypernatremia. His blood sodium rised from 136 mmol/L on admission to 152 mmol/L. After stopping tolvaptan, the serum sodium level continued to rise, with a peak value of 168 mmol/L. After relaxing his water intake restriction, serum sodium gradually decreased to 160 mmol/L. On the 4th day of drug withdrawal, dapagliflozin (5 mg orally once daily) was added; on the 5th day, the blood sodium was 146 mmol/L.

A 79-year-old male patient with diabetes mellitus was given tolvaptan (15 mg orally once daily) combined with furosemide, levosimendan, and recombinant human brain natriuretic peptide for heart failure 7 years after coronary artery bypass grafting and clopidogrel, metoprolol, ezetimibe, insulin glargine, and liraglutide were given concomitantly for coronary atherosclerotic heart disease and diabetes mellitus. Three days later, his heart failure symptoms were improved, but he developed hypernatremia. His blood sodium rised from 136 mmol/L on admission to 152 mmol/L. After stopping tolvaptan, the serum sodium level continued to rise, with a peak value of 168 mmol/L. After relaxing his water intake restriction, serum sodium gradually decreased to 160 mmol/L. On the 4th day of drug withdrawal, dapagliflozin (5 mg orally once daily) was added; on the 5th day, the blood sodium was 146 mmol/L.