OBJECTIVES: Cognitive and neurologic dysfunction, the most common physiological manifestations of hyponatremia, can significantly impair individuals’ health-related quality of life (HRQOL). Therapeutic correction of hyponatremia should focus not only on normalization of serum sodium, but improvement of patients’ functional utility as well. We examined the average change in utility scores from initiation of either tolvaptan therapy or standard of care (SOC) to day-7 and day-30 post-initiation. Standardized utility scores were derived from SF-12 scores from pooled SALT (Study of Ascending Levels of Tolvaptan in Hyponatremia) I and II data. METHODS: SF-12 scores were mapped to the EQ-5D and utility scores were derived using methodology developed by Gray, et.al, 2006. Mean change from baseline was assessed for both tolvaptan and standard of care (SOC) patient cohorts at day-7 and day-30, quantified as both absolute and percent change. Differences from baseline to day-7 and day-30 were assessed using a student’s t test.     RESULTS: All patients in the SALT trials had a baseline serum sodium <135 mEq/L. From baseline to day-7, the mean increase in utility score for tolvaptan patients (n=180) was 0.084, compared to an increase of 0.032 for patients receiving SOC (n=163) (p=0.183). A statistically significant mean increase in utility was associated with tolvaptan use from baseline to day 30 post-therapy initiation compared with SOC (p=0.005).  The mean increase in utility score at day 30 for patients receiving tolvaptan (n=150) was 0.108, whereas utility scores for patients receiving SOC (n=164) had returned to baseline values by day-30, with a mean change from baseline of 0.001. CONCLUSIONS: Tolvaptan use for hyponatremia is associated with an increase in utility compared with SOC, evident at day-7 and statistically significant (p=0.005) at day-30. Utility for tolvaptan patients increased from day-7 to day-30 while those for SOC decreased to baseline during this period.