FGF23 and secondary hyperparathyroidism: FGF23 elevation in CKD is associated with several adverse outcomes, including: (1) greater risk of end stage renal disease (ESRD) (if eGFR > 30 mL/min/1.73 m2) [30]; (2) faster progression to refractory secondary hyperparathyroidism [108]; (3) left ventricular hypertrophy [114,115] and (4) higher mortality rate in dialysis patients [116,117].