Hyponatremia is the commonest electrolyte abnormality in hospitalized patients [1]. Patients with decompensated heart failure (HF) commonly have electrolyte abnormalities, due to the activation of several neurohumoral mechanisms, in addition to effect of drugs especially diuretics [2]. Hyponatremia is evident on hospital admission in ~15–25% of patients with decompensated HF [3–6], and to a similar extent throughout hospitalization [7,8]. Although extensively studied in HF, the majority of research focused on the prognostic value of hyponatremia on admission [3], behavior of sodium (Na+) level from admission to discharge [6], and decreasing Na+ after discharge [9], and in those instances, hyponatremia was found to be associated with worse outcomes.
