PURPOSE OF REVIEW: Description of the recent advances on the regulation of 
phosphate metabolism, gene mutations, and new approaches to treatment in 
patients with hypophosphatemic rickets.
RECENT FINDINGS: Fibroblast growth factor 23 (FGF23) overproduction may be a 
primary cause of hypophosphatemic rickets. Inactivating mutations of 
phosphate-regulating gene with homologies to endopeptidases on the X chromosome, 
dentin matrix acidic phosphoprotein 1, and ectonucleotide 
pyrophosphatase/phosphodiesterase 1 are associated with X-linked 
hypophosphatemic rickets, autosomal recessive hypophosphatemic rickets 1, and 
autosomal recessive hypophosphatemic rickets 2, respectively. Activating 
mutations of FGF23 gene is the cause of autosomal dominant hypophosphatemic 
rickets. Iron deficiency may affect autosomal dominant hypophosphatemic rickets 
phenotype by regulating FGF23 production.Current treatment with activated 
vitamin D metabolites and oral inorganic phosphate salts may partially correct 
skeletal lesions and linear growth in patients with hypophosphatemic rickets. 
However, some patients have poor improvement by the current treatment.
SUMMARY: Identification of the causative mutation in patients with 
hypophosphatemic rickets may be useful to confirm the diagnosis and probably for 
prognosis. Inhibition of FGF23 overproduction by anti-FGF23 neutralizing 
antibodies could be a future approach for treatment of patients with 
FGF23-dependent hypophosphatemic rickets.