Tolvaptan treatment is associated with altered mineral metabolism parameters and increased bone mineral density in ADPKD patients.

Abstract

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by a unique bone and mineral phenotype. The impact of tolvaptan treatment on mineral metabolism and bone mineral density (BMD) is unknown. We conducted an analysis in the Bern ADPKD Registry, a prospective observational cohort study. Mineral metabolism parameters were measured at baseline and every 12months thereafter. BMD was determined by dual-energy X-ray absorptiometry at baseline and after 3years. Multivariable mixed-effects regression models were applied to assess changes in mineral metabolism parameters and BMD associated with tolvaptan treatment. A total of 189 participants (122 without and 67 with subsequent tolvaptan treatment) were included in the analysis. During follow-up, tolvaptan treatment was associated with increased BMD at the femoral neck {β=0.092 [95% confidence interval (CI) 0.001-0.183], P=.047}. In addition, tolvaptan treatment was associated with higher plasma magnesium [β=0.019 (95% CI 0.001-0.037), P=.037], bicarbonate [β=0.972 (95% CI 0.242-1.702), P=.009] and urine pH [β=0.214 (95% CI 0.056-0.372), P=.008] and lower parathyroid hormone [β=-0.191 (95% CI -0.328 to -0.053), P=.006], 1,25(OH)D3 [β=-0.126 (95% CI -0.235 to -0.164), P=.024] and fractional urinary magnesium excretion [β=-0.473 (95% CI -0.622 to -0.324), P<.001]. Chronic tolvaptan treatment is associated with increased femoral BMD and significant changes in both mineral metabolism and acid-base parameters in ADPKD patients.