Limited data suggest that cinacalcet, a calcimimetic, may be able to ameliorate the hyperparathyroidism in some patients with XLH.70, 71, 72 Phosphate dosing causes temporary rises of PTH, but single doses of cinacalcet to children with XLH without hyperparathyroidism blocked the rise in PTH after a subsequent phosphate dose.72 Furthermore, PTH stimulates FGF23 secretion from osteocytes.73 So modulating PTH might have some effects to decrease FGF23 or at the very least could decrease the PTH effect on the proximal renal tubule to promote phosphaturia. Here, FGF23 is linked to hyperparathyroidism.