There has been a lot of buzz surrounding the recent NEJM article by Gutiérrez (a recently graduated fellow from my program!) et al regarding the potential role of measuring FGF23 levels as an important biomarker in patients with ESRD.
FGF23, as detailed elsewhere in this blog, is felt to be the main phosphaturic hormone which regulates in vivo phosphorus balance. In a nest case-control sample consisting of 200 dialysis patients who died within the first year of initating dialysis and 200 dialysis patients who survived their first year of dialysis, it was determined that FGF23 levels were markedly elevated in the group who died within one year.
Obviously, this remains an association and does not imply causality. Indeed, one might postulate that the higher FGF23 group was sicker because they waited until uremic to begin dialysis. However, FGF23 remained associated with a higher mortality even when adjusted for phosphorus level, and the authors suggest that FGF23 may be a biomarker to determine which patients with CKD may be at risk for a high cardiovascular mortality and might benefit from early treatment with phosphorus binders.