Shunji Suzuki, Norio Hanafusa, Kenji Kubota, Ken Tsuchiya, Kosaku Nitta

Fluid overload in chronic kidney disease (CKD) is generally controlled by diuretics, with potentially harmful effects on renal function. The efficacy of tolvaptan, a vasopressin V2-receptor antagonist and aquaretic, has not been evaluated for fluid control in CKD with reduced renal function. Each patient from a group of 24 CKD patients on tolvaptan 15 mg/d plus conventional diuretics (T group) was matched by age and sex with a patient from a group of 24 CKD patients on conventional nonaquaretic diuretics alone not associated to tolvaptan other than tolvaptan (C group). Changes in renal function were compared between the groups for 1 year. There were no significant differences in blood pressure, hemoglobin levels, cardiac function, urine specific gravity, and urinary sodium concentration between the 2 groups at the beginning of the follow-up period and 1 year after. The estimated glomerular filtration rate (eGFR) by the formula developed by Japanese Society of Nephrology (in mL/min/1.73 m2) decreased: C group (from 28.3±13.6 to 23.0±12.3, p=0.09), T group (from 22.7±12.4 to 19.4±12.2, p=0.18), but both did not reach significance. A 50% reduction in eGFR was observed in 4 patients in the C group and 1 in the T group (p<0.05). A subgroup analysis performed on the patients with stage 3-4 CKD demonstrated a significant reduction in eGFR in the C group (n=17, p=0.04), but not in T group (n=17, p=0.07). These results suggest that tolvaptan may have less effects on CKD progression among stage 3-4 CKD patients who are on conventional diuretics.