Increased plasma arginine vasopressin levels in dopamine agonist-treated Parkinson's disease patients

OBJECTIVE: Several cases of syndrome of inappropriate antidiuresis induced by antiparkinson agents have been previously reported. However, the effect of antiparkinson agents on plasma arginine vasopressin (AVP) levels remains unknown in Parkinson's disease (PD) patients. The aim of the present study is to determine plasma AVP levels in PD patients and the effects of antiparkinson agents on these levels. METHODS: PD patients who visited our clinic between November 2008 and September 2009 were included in this study. Patients were excluded if they had at least one condition that could be associated with high AVP levels. PD patients who had been treated with antiparkinson agents participated in this study (treated PD group, n=76). De novo PD patients were also included (n=25). RESULTS: Mean plasma AVP levels were significantly higher in treated PD patients than those in treatment-naive patients. Neither disease severity nor L-dopa dosage correlated with plasma AVP levels. Multiple linear regression analysis identified the male gender and pergolide dosage as weak independent predictors of high plasma AVP levels. While no difference in plasma AVP levels between genders in treatment-naive patients was observed, mean plasma AVP levels were significantly higher in male patients than in female patients administered antiparkinson agents. Mean plasma AVP levels in pergolide users were significantly higher than those in dopamine agonist nonusers with corresponding disease duration and L-dopa/carbidopa dosage. In some patients, plasma AVP levels appeared to be dependent on pramipexole dosage. CONCLUSION: Dopamine agonists may cause increased plasma AVP levels in some PD patients.