Tonelli M, et al. - In view of the common occurrence of deficiency of essential trace elements and excess of potentially toxic trace elements in patients on hemodialysis, researchers searched for the association of these abnormalities with poor outcomes, as they are potentially treatable. Lower levels of zinc or manganese and higher concentrations of lead, arsenic, or mercury were not observed to have any association with higher risk of clinical outcomes. However, lower concentrations of selenium demonstrated strong and independent association with the risks of death and hospitalization.