Magnetic resonance imaging is effective for evaluating the therapeutic effect of tolvaptan on total kidney volume in patients with autosomal dominant polycystic kidney disease

Abstract

Background: Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited disease among primary diseases in dialysis patients. Tolvaptan is known to improve increases in total kidney volume (TKV) in patients with ADPKD, thereby slowing the progression of kidney dysfunction. However, TKV is not always measured using magnetic resonance imaging (MRI), and the specific effect of tolvaptan has yet to be determined. Case presentation: We examined six patients (four males and two females) who underwent tolvaptan treatment at the Higashi-Hiroshima Medical Center. TKV was measured by volumetry using magnetic resonance imaging (MRI) at three time points (before, at the time of, and 1 year after the start of tolvaptan treatment). The rates of change in TKV and estimated glomerular filtration rate (eGFR) were also measured before and at the start of treatment, and values at the start of treatment and after treatment were compared. Data were analyzed using Wilcoxon's signed-rank test. After the start of tolvaptan treatment, the rates of change in TKV were significantly decreased compared with those before treatment (before treatment, 9.2 mL/min/1.73 m2/year [range 7.4-10.2]; after treatment, 2.4 mL/min/1.73 m2/year [range 0.8-5.9], P = 0.031). The rates of change in eGFR were not significantly different after the start of tolvaptan treatment (before treatment, 9.2 mL/min/1.73 m2/year [range 7.4-10.2]; after treatment, 2.4 mL/min/1.73 m2/year [range 0.8-5.9], P = 0.58). Conclusions: MRI enables accurate evaluation of the initial therapeutic effect of tolvaptan on TKV in Japanese ADPKD patients.