MATERIAL AND METHODS
Study Design and Setting
From June 2011 to August 2013, consecutive eligible individuals
presenting to the emergency department of the
University Hospital Basel, Basel, Switzerland, and the University
Medical Clinic Aarau, Aarau, Switzerland, with
profound hyponatremia were included in this prospective
observational study. Profound hyponatremia was defined
as a serum sodium level of less than 125 mmol/L. The ethics
committees of Basel and Aarau approved the study protocol,
and informed consent was obtained from all
participants. The study was preregistered on clinicaltrials.gov
(identifier NCT01456533).