Association Between the Serum Sodium Levels and the Response to Tolvaptan in Liver Cirrhosis Patients with Ascites and Hyponatremia

Objective Hyponatremia is closely associated with the pathophysiology of cirrhosis. However, the association between the serum sodium level and the response to tolvaptan is unclear. This study evaluated the factors related to the tolvaptan response and the prognosis in cirrhosis patients with ascites and hyponatremia. Methods We retrospectively reviewed the clinical records of cirrhosis patients hospitalized for treatment with tolvaptan. The associations of patient baseline characteristics with the tolvaptan response after one week and of the characteristics after one-month tolvaptan treatment with the prognosis were analyzed. Results We analyzed 83 cirrhosis patients with ascites, including 34 patients with hyponatremia. The response rates to tolvaptan in patients with serum sodium <130 mEq/L, 130-135 mEq/L, and >135 mEq/L were 20%, 66%, and 58%, respectively (p=0.22). The serum sodium level was associated with the response to tolvaptan [odds ratio=1.18; 95% confidence interval (CI) =1.02-1.37; p=0.029]. In patients with hyponatremia, the serum sodium level after 1-month tolvaptan treatment was increased compared to baseline (132 mEq/L vs. 136 mEq/L, p=0.006), and an increasing serum sodium level was associated with a lower risk of mortality (hazard ratio=0.85; 95% CI=0.75-0.97; p=0.016). The survival rate was higher in patients with an increase in the serum sodium level after 1 month than in patients with a decreased serum sodium level (p=0.023). Conclusion Tolvaptan treatment was effective in cirrhosis patients with ascites and hyponatremia, but a low serum sodium level was associated with non-responsiveness to tolvaptan. An increased serum sodium level after one-month tolvaptan treatment may positively influence the mortality risk in cirrhosis patients with hyponatremia.