Author’s Reply to Correspondence: “Effect of Tolvaptan Treatment on Acid−Base Homeostasis in ADPKD Patients”

We thank Matteo Bargagli and his colleagues for their interest in our study and suggestion to investigate the urinary citrate excretion as a more sensitive measure of change in acid−base regulation than plasma bicarbonate. In their study, they describe urinary citrate excretion to be higher and net renal acid excretion to be lower in ADPKD patients using tolvaptan compared to ADPKD patients without tolvaptan.¹ Direct comparison of results is hampered by the fact that both studies have not measured the entire acid−base profile. We did not measure urinary citrate and net renal acid excretion, which would have been valuable additions, and Bargagli and colleagues did not measure plasma pH, bicarbonate, and pCO₂. However, results of these 2 studies are consistent in their rejection of our primary hypothesis. Tolvaptan does not seem to induce an increase in bicarbonate reabsorption in the investigated patients.