Aratani S, et al. - This study intended to shed light on the risks for overcorrection during the treatment of chronic profound hyponatremia. In patients with profound hyponatremia, a link was evident between an initial low level of serum sodium (SNa) and an increased risk of overcorrection. It was also observed that, in this regard, the rapid increase in SNa during the first 4 h may play a crucial role.