Downloadable materials


Publications of Interest

  • Haffner D, et al. Clinical practice recommendations for the diagnosis and management of X-linked hypophosphataemia. Nat Rev Nephrol. 2019 Jul;15(7):435-455.
    PubMed link:
  • Imel EA, et al. Burosumab versus conventional therapy in children with X-linked hypophosphataemia: a randomised, active controlled, open-label, phase 3 trial. Lancet. 2019 Jun 15;393(10189):2416-2427.
    PubMed link:
  • Whyte MP, et al. Efficacy and safety of burosumab in children aged 1–4 years with X-linked hypophosphataemia: a multicentre, open-label, phase 2 trial. Lancet Diabetes Endocrinol. 2019 Mar;7(3):189-199.
    PubMed link:
  • Beck-Nielsen SS, et al. FGF23 and its role in X-linked hypophosphatemia-related morbidity. Orphanet J Rare Dis. 2019 Feb 26;14(1):58.
    PubMed link:
  • Carpenter TO, et al. Burosumab therapy in children with X-Linked hypophosphatemia. N Engl J Med. 2018 May 24;378(21):1987-1998.
    PubMed link:

Key Facts about XLH and CRYSVITA

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What is XLH?

X-linked hypophosphataemia (XLH) is a rare, hereditary, progressive and lifelong phosphate wasting disorder, caused by mutations in the PHEX (phosphate-regulating endopeptidase homolog, X-linked) gene that leads to excess fibroblast growth factor 23 (FGF23)1-4

What is the prevalence?
XLH is a rare disease that affects approximately 1 in 20,000 - 60,000 people1,5
How is it inherited?

XLH is inherited in an X-linked dominant pattern; however, 20-30% of cases arise from spontaneous mutations6-8

What is XLH caused by?

XLH is caused by mutations in the PHEX gene4,5 which is located on the X chromosome

What does it mean for patients with XLH?

Excess FGF23:

  • Decreases renal phosphate reabsorption, which increases urinary phosphate excretion
  • Decreases active vitamin D (1,25[OH]2D) production, which reduces intestinal phosphate absorption

The resulting chronic hypophosphataemia impairs bone mineralisation, leading to a variety of clinical manifestations that can impair patients’ physical function and quality of life9

XLH is not just a bone disease – it is a multisystemic disease that impacts muscle and dentition as well4,10



CRYSVITA is a recombinant, fully human monoclonal antibody (IgG1) that binds to and inhibits excess FGF23 activity11
It is the first and only disease-modifying biologic treatment that targets the pathophysiology of XLH11

How does CRYSVITA work?

By inhibiting excess FGF23 activity, CRYSVITA helps restore phosphate homeostasis in children with XLH and improve bone mineralisation11-12

Who can receive CRYSVITA?

CRYSVITA is indicated for the treatment of XLH with radiographic evidence of bone disease in children ≥ 1 years and adolescents with growing skeletons11


The efficacy and safety of CRYSVITA in children aged 1-12 years with XLH have been studied in a global clinical development programme.12-14
A phase 3 clinical study showed that compared with continuing conventional therapy, switching children with XLH to CRYSVITA:12

  • Significantly improved rickets healing and reduced severity
  • Significantly improved growth and mobility outcomes
  • Significantly improved biochemical markers of phosphate regulation and bone health

CRYSVITA has an acceptable safety profile over 64 weeks in children with XLH12

Useful websites

XLH information websites for healthcare professionals

XLH Link (Healthcare professional website). This website is developed and funded by Kyowa Kirin International.

European Society for Paediatric Endocrinology

European Calcified Tissue Society

European Society for Paediatric Nephrology

XLH information websites for patients

XLH Link (Patient website). This website is developed and funded by Kyowa Kirin International.

XLH Alliance Founded in 2018, the XLH Alliance is an alliance of patient groups for individuals affected by X-linked hypophosphatemia and related disorders. The XLH Alliance will direct you to organisations in your country that can provide information, education and a community to join that could provide support to patients and their families.

1. Beck-Nielsen SS, et al. Eur J Endocrinol. 2009;160:491–497. 2. Endo I, et al. Endocr J. 2015;62(9):811–816 3. Carpenter TO, et al. J Bone Miner Res. 2011;26:1381–1388. 4. Haffner D, et al. Nat Rev Nephrol. 2019;15:435–455. 5. Rafaelsen S, et al. Eur J Endocrinol. 2016;174(2):125–136. 6. Whyte MP, et al. J Clin Endocrinol Metab. 1996;81(11):4075–4080. 7. Rajah J, et al. Eur J Pediatr. 2011;170:1089-1096. 8. Dixon PH, et al. J Clin Endocrinol Metab. 1998;83(10):3615–3623. 9. Linglart A, et al. Endocr Connect. 2014;3:R13–R30. 10. Beck-Nielsen SS, et al. Orphanet J Rare Dis. 2019;14(1):58. 11. CRYSVITA (burosumab). Summary of Product Characteristics. February 2019. 12. Imel EA, et al. Lancet. 2019;393:2416–2427. 13. Carpenter TO, et al. N Engl J Med. 2018;378:1987-1998. 14. Whyte MP, et al. Lancet Diabetes Endocrinol. 2019;7:189-199.

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