Background: The syndrome of inappropriate antidiuresis (SIAD) is characterized by a reduction of free water excretion with consecutive hypotonic hyponatremia and is therefore challenging to treat. The sodium-glucose cotransporter 2 (SGLT2) inhibitor empagliflozin promotes osmotic diuresis via urinary glucose excretion, likely leading to increased electrolyte free water clearance.
Methods: In this randomized, double-blind, placebo-controlled, crossover trial, we compared 4-week treatment with empagliflozin 25 mg/d to placebo in outpatients with chronic SIAD-induced hyponatremia. At baseline and after both treatment cycles, patients underwent different assessments including neurocognitive testing (Montreal Cognitive Assessment [MoCA]). The primary end point was the difference in serum sodium levels between treatments.
Results: Fourteen patients, 50% female, with a median age of 72 years (interquartile range [IQR], 65-77), completed the trial. Median serum sodium level at baseline was 131 mmol/L (IQR, 130-132). After treatment with empagliflozin, median serum sodium level rose to 134 mmol/L (IQR, 132-136), whereas no increase was seen with placebo (130 mmol/L; IQR, 128-132), corresponding to a serum sodium increase of 4.1 mmol/L (95% confidence interval [CI], 1.7 to 6.5; P =0.004). Exploratory analyses showed that treatment with empagliflozin led to improved neurocognitive function with an increase of 1.16 (95% CI, 0.05 to 2.26) in the MoCA score. Treatment was well tolerated; no serious adverse events were reported.
Conclusion: The SGLT2 inhibitor empagliflozin is a promising new treatment option for chronic SIAD-induced hyponatremia, possibly improving neurocognitive function. Larger studies are needed to confirm the observed treatment effects.
Clinical trial registration number: ClinicalTrials.gov NCT03202667.
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