Background: Tolvaptan selectively binds to the vasopressin V2 receptor and inhibits reabsorption of free water. Although its efficacy for heart failure has been proven, its efficacy for chronic kidney disease (CKD) patients has not been assessed in detail.
Methods: We examined 20 CKD patients (13 men and 7 women) who presented with volume overload and who were administered tolvaptan. We assessed urine volume (UV) and blood biochemistry before administration (dO), 1 day after administration (d1), and 7 to 14 days after administration (d7-14).
Results: The mean age was 74.0 +/- 13.1 years. Besides CKD, there were 9, 8, and 5 patients with heart failure, liver failure or liver cirrhosis, andsevere oedema, respectively. UV significantly increased from 959.0 +/- 503.8 mL/day at d0 to 1605.4 +/- 964.0 mL/day at d7-14 (P<0.01). Serum creatinine levels were not exacerbated (3.89 +/- 3.43 mg/dL at d0 and 3.66 +/- 3.02 mg/dL at d7-14). Serum albumin (ALB) levels and urinary protein creatinine ratio (uPCR) did not correlate with UV change. Estimated glomerular filtration rate (eGFR) correlated with UV change from d0 to d1 (r=0.6619, P<0.01). Serum sodium elevation correlated with increased UV (r=0.4951, P<0.05).
Conclusion: Tolvaptan is useful to reduce volume overload without exacerbation of the renal function; its effect does not depend on ALB or uPCR. the eGFR correlated with the efficacy of tolvaptan. If UV increases drastically after tolvaptan administration, serum Na levels should be carefully monitored.