Severe hyponatremia secondary to syndrome of inappropriate antidiuretic hormone (SIADH): A rare cause of takotsubo (stress) cardiomyopathy.

Takotsubo cardiomyopathy is a reversible, stress-induced systolic abnormality of the left ventricular apex.1,2 It can carry significant morbidity and mortality for patients, largely due to associated complications that can occur in the acute setting. While it is most commonly linked with acute emotional or physical stressors, it is now recognized that many acute medical illnesses can precipitate the syndrome. Severe acute hyponatremia (<120 mmol/L) should be considered as a possible causative condition for Takotsubo cardiomyopathy, however reports of its occurrence in the literature are exceedingly rare.3-14 We present a case of a 73-year-old woman who was admitted for severe hyponatremia secondary to syndrome of inappropriate anti-diuretic hormone (SIADH) with a sodium level of 105 mmol/L and a concomitant diagnosis of Takotsubo cardiomyopathy, as well as a review of the epidemiology, pathophysiology, clinical features, diagnosis, treatment and clinical outcomes of Takotsubo cardiomyopathy.