FGF23 and X-linked hypophosphatemia: In addition, our previous study (4) showed that, compared with patients with XLH, patients with TIR/O had a significantly higher level of serum FGF23, a significantly lower level of serum phosphate, and a significantly lower level of areal bone mineral density (aBMD) as evaluated by dual-energy X-ray absorptiometry (DXA).