An editorial discusses the current opinions on potassium levels “although the exact level of serum potassium that is associated with an increase in mortality remains controversial, increasing evidence suggests that in patients with chronic kidney disease (CKD), diabetes mellitus, and/or heart failure, especially the elderly, a K+ >5.0 mmol/L is associated with an increased risk of death. Conversely, while a K+ <3.5 mmol/L is thought by many to be associated with an increase in mortality in patients with heart failure, there is evidence that a K+ <4.0 mmol/L is associated with an increase in mortality and that most deaths due to hypokalaemia in patients with heart failure occur with a K+ <4.0–3.5 mmol/L.5,6 Despite this evidence in patients with heart failure and/or CKD a K+ <4.0 mmol/L is often not corrected.”It also highlights the limitations of this study including its observational nature and lack of information on cause of death.