Comparison of tolvaptan treatment between patients with the SIADH and congestive heart failure: a single-center experience

Background/Aims: Tolvaptan is a very effective treatment for hypervolemic or euvolemic hyponatremia. We compared the clinical efficacy of and response to tolvaptan in patients with the syndrome of inappropriate antidiuretic hormone secretion (SIADH) and congestive heart failure (CHF). Methods: We retrospectively reviewed the medical records of 50 patients (SIADH, n = 30; CHF, n = 20) who were prescribed tolvaptan between July 2013 and October 2015. Tolvaptan was prescribed when the serum sodium level was < 125 mmol/L and the standard treatment failed. Normonatremia was defined as a serum sodium level of > 135 mmol/L. Results: After the initiation of tolvaptan therapy, there was an immediate response in the urine volume and serum sodium level in all patients. The improvements in the urine volume and serum sodium concentration were highest within the first 24 hours of treatment. In addition, the mean change in the serum sodium level during the first 24 hours was significantly higher in patients with SIADH than in those with CHF (${\Delta}Na$, $9.9{\pm}4.5mmol/L$ vs. $6.9{\pm}4.4mmol/L$, respectively; p = 0.025). Also, the mean maintenance dose was lower, and the total duration of tolvaptan use was slightly shorter in the SIADH group than CHF group ($21.5{\pm}14.9days$ vs. $28.0{\pm}20.1days$, p = 0.070). Conclusions: The early response to tolvaptan treatment was better in patients with SIADH than in those with CHF. Thus, the tolvaptan treatment strategy should be differed between patients with SIADH and those with CHF.