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

ABSTRACT Background 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. Methods We conducted an analysis in the Bern ADPKD Registry, a prospective observational cohort study. Mineral metabolism parameters were measured at baseline and every 12 months thereafter. BMD was determined by dual-energy X-ray absorptiometry at baseline and after 3 years. Multivariable mixed-effects regression models were applied to assess changes in mineral metabolism parameters and BMD associated with tolvaptan treatment. Results 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