FGF23 and cellulitis: In chronic kidney disease, another condition with elevated circulating FGF23, high FGF23 serum level associates with increased risk of infection.(31) It has been observed that high level of FGF23 can modulate neutrophils and other leukocytes’ function and recruitment and impair the immune response.(32, 33) The elevated FGF23 in XLH could contribute in this way to the development of an infection and its rapid diffusion into soft tissue to evolve into cellulitis.