XLH is X-linked hypophosphataemia.

Mechanism of disease

What does XLH look like in action?

Role of FGF23

FGF23 is a protein hormone that regulates serum phosphate levels by suppressing both phosphate reabsorption in the kidney intestinal absorption of dietary phosphate. ^6,7

In patients with XLH, excess FGF23 leads to chronic hypophosphataemia caused by renal phosphate wasting and decreased intestinal absorption of phosphate ^1,12,13

Low serum phosphate concentrations and reduced tubular reabsorption of phosphate corrected for glomerular filtration rate (GFR) are the characteristic laboratory findings in XLH patients ¹

References

1. Ruppe, MD. X-linked hypophosphatemia. In: Pagon RA, Adam MP, Ardinger HH, et al, eds. Gene Reviews. https://www.ncbi.nlm.nih.gov/books/NBK83985/. Accessed October 20, 2017. 2. Hereditary Hypophosphataemic rickets. NIH Genetics Home Reference Web site. https://ghr.nlm.nih.gov/condition/hereditary-Hypophosphataemic-rickets. Accessed October 11, 2017. 3. Jackson WPU, Dowdle E, Linder GC. Vitamin-D-resistant osteomalacia. Brit Med J. 1958:1269-1274. 4. Rickets and osteomalacia. NHS Choices Web site. https://www.nhs.uk/Conditions/Rickets/Pages/Treatment. Accessed October 11, 2017. 5. Familial Hypophosphatemia. National Organization for Rare Disorders Web site. https://rarediseases.org/rare-diseases/familial-hypophosphatemia/. Accessed October 11, 2017. 6. Martin A, Quarles LD. Evidence for FGF23 involvement in a bone-kidney axis regulating bone mineralization and systemic phosphate and vitamin D homeostasis. Adv Exp Med Biol. 2012;728:65-83. 7. Schiavi SC. Fibroblast growth factor 23: the making of a hormone. Kidney Int. 2006;69(3):425-427. 8. Riminucci M, Collins MT, Fedarko NS, et al. FGF-23 in fibrous dysplasia of bone and its relationship to renal phosphate wasting. J Clin Invest. 2003;112(5):683-692. 9. Ferrari SL, Bonjour J-P, Rizzoli R. Fibroblast growth factor-23 relationship to dietary phosphate and renal phosphate handling in healthy young men. J Clin Endocrinol Metab. 2005;90(3):1519-1524. 10. Che H, Roux C, Etcheto A, et al. Impaired quality of life in adults with X-linked hypophosphatemia and skeletal symptoms. Eur J Endocrinol. 2016;174(3):325-333. 11. Gattineni J, Bates C, Twombley K, et al. FGF23 decreases renal NaPi-2a and NaPi-2c expression and induces hypophosphatemia in vivo predominantly via FGF receptor 1. Am J Physiol Renal Physiol. 2009;297(2):F282-F291. 12. Carpenter TO, Imel EA, Holm IA, Jan de Beur SM, Insogna KL. A clinician’s guide to X-linked hypophosphatemia. J Bone Miner Res. 2011;26(7):1381-1388. 13. Penido MG, Alon US. Phosphate homeostasis and its role in bone health. Pediatr Nephrol. 2012;27(11):2039-2048.