Successful treatment with tolvaptan to control blood volume and hyponatremia in a chronic kidney disease patient.

We report a case of successful treatment with tolvaptan (15 mg/day) in a 73-year-old female patient with chronic kidney disease (CKD) stage 5 due to diabetic nephropathy and renal sclerosis for volume control and loop diuretic-induced hyponatremia. Her creatinine clearance has remained at 7-10 ml/min for the last 6 months. She was treated by dietary and drug therapy, namely, antihypertensives (nifedipine: 40 mg/day, olmesartan: 20 mg/day) and loop diuretics (azosemide: 40-120 mg/day), for CKD and concomitant diseases of hypertension and diabetic mellitus. She developed loop diuretic-induced hyponatremia (120 mmol/l) by increased sodium excretion, but the diuretic was required for the control of volume overload. Hence, azosemide was suspended and tolvaptan (15 mg/day) was administered. After tolvaptan treatment, the plasma sodium level gradually increased to a normal level (135-140 mmol/l) and volume overload was improved. Urine volume was maintained at about 1000 ml/day with low sodium excretion (<40 mmol/day) and increased free water clearance. These results suggest that tolvaptan may be effective for volume control and diuretic-induced hyponatremia in CKD patients.