[A brief update on FGF23 for the clinical nephrologist]

Fibroblast growth factor-23 (FGF23) is a hormone that controls homeostasis of calcium and phosphate metabolism in health and disease. Unlike most other hormones, FGF23 rises exponentially with declining kidney function, reaching extreme elevations in many end-stage renal disease patients. Clinical and experimental data further suggest that FGF23 is a very early biomarker of kidney injury, and its predictive value of adverse clinical outcomes has been confirmed across the entire spectrum of chronic kidney disease, including pre-dialysis and dialysis populations as well as renal transplant recipients. The questions if, how and when FGF23 will impact future clinical practice in nephrology remain open. Several putative trajectories have been outlined, including the use of FGF23 as a biomarker for selection of treatment, enrichment strategies in clinical trials, but also direct blockade of FGF23 signaling as a treatment target on its own. In this condensed review, we provide an update on FGF23 and briefly discuss its current and potential future role in chronic kidney disease.