Arévalo-Lorido JC, Carretero-Gómez J, Robles NR, et al. - Among heart failure (HF) patients in whom the presence or absence renal insufficiency was precisely predefined, researchers focused on the prognostic role of hyponatremia based on renal disease in this cohort study based on the Spanish National Registry on Heart Failure (a multicenter, prospective registry that registers patients admitted for decompensated HF who were subsequently observed for 1 year). Findings revealed a greater prevalence of hyponatremia in patients with renal insufficiency, and the co-occurrence of renal disease and hyponatremia led to poorest outcome. There were no differences in outcome between patients with hyponatremia without renal disease vs those without hyponatremia.