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Anti-FGF23 Monoclonal Antibody (X-Linked Hypophosphataemia)

Burosumab

Brand names: Crysvita

Burosumab is a recombinant monoclonal antibody against fibroblast growth factor 23 (FGF23) used to treat X-linked hypophosphataemia and FGF23-related tumour-induced osteomalacia.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

It binds and inhibits excess FGF23, restoring renal phosphate reabsorption and increasing 1,25-dihydroxyvitamin D production, thereby normalising serum phosphate and improving bone mineralisation.

Prescribing in practice

  • Stop oral phosphate and active vitamin D analogues before starting, and avoid combining them with burosumab, because of the risk of hyperphosphataemia and nephrocalcinosis.
  • It is contraindicated in significant renal impairment and should not be used with serum phosphate already in or above the normal range for age.
  • Doses are titrated against fasting serum phosphate, which should be kept within the lower part of the reference range to limit ectopic mineralisation.

Monitoring

Monitor fasting serum phosphate regularly, together with calcium, vitamin D and renal ultrasound for nephrocalcinosis as indicated.

Counselling the patient

  • Do not take phosphate or active vitamin D supplements while on this treatment unless told to.
  • Attend for the blood tests used to adjust your dose.
  • Report injection-site reactions or restless legs.

Evidence & guidelines

Burosumab for X-linked hypophosphataemia is supported by pivotal randomised trials and is recommended by NICE within specialist services.

Reference: Carpenter et al. NEJM 2018 (paediatric XLH); NICE TA745 (burosumab); MHRA SPC Crysvita; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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