An injection for X-linked hypophosphataemia
Burosumab
A regular injection used to correct low phosphate in X-linked hypophosphataemia, helping to strengthen bones.
What is Burosumab?
Burosumab is a specialist injection used to treat X-linked hypophosphataemia, an inherited condition in which the body loses too much phosphate in the urine, leading to soft, weak bones (rickets in children and bone pain in adults). It works by blocking a hormone called FGF23 that drives this phosphate loss, so phosphate levels rise and bones can strengthen. It is given as an injection under the skin every few weeks. Importantly, it must not be used together with oral phosphate supplements or active vitamin D, and phosphate levels are monitored to avoid them rising too high.
Education and reference only. This is a plain-language guide to Burosumab — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Burosumab is a medicine used to treat X-linked hypophosphataemia, an inherited condition in which the kidneys waste phosphate, an essential mineral for healthy bones. The low phosphate causes rickets and bone deformity in children and bone pain and weakness in adults. Burosumab is an antibody that blocks the hormone responsible for the phosphate loss, allowing phosphate levels to recover. It is given as an injection under the skin on a regular schedule, under specialist supervision. It is used instead of, not alongside, the older treatment with phosphate supplements and active vitamin D.
How it works
In X-linked hypophosphataemia, the body produces too much of a hormone called FGF23, which tells the kidneys to get rid of phosphate and reduces the activation of vitamin D. The result is persistently low phosphate and poorly mineralised bone. Burosumab attaches to FGF23 and blocks its action, so the kidneys hold on to more phosphate and vitamin D works more normally, helping bones mineralise and heal. Because it raises phosphate, the level is monitored, and it is not combined with phosphate supplements or active vitamin D, which would push phosphate too high.
Company & origin
Originated / developed by: Specialist manufacturer.
A specialist injection used in the UK to treat X-linked hypophosphataemia, an inherited condition that causes low phosphate levels and weak bones.
Practical use
How to take Burosumab
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- It is given as an injection under the skin every few weeks, as arranged by your specialist team.
- Stop oral phosphate supplements and active vitamin D before starting, as these must not be combined with burosumab.
- Attend regular blood tests to check your phosphate level so the dose can be adjusted safely.
- Tell your team about all supplements and medicines, especially anything containing phosphate or vitamin D.
- Report ongoing bone pain, muscle symptoms or injection-site problems at your reviews.
Weighing it up
Advantages & disadvantages of Burosumab
Advantages
- Targets the underlying cause of phosphate loss in X-linked hypophosphataemia.
- Can improve rickets, bone healing and bone pain better than the older supplement approach for many people.
- Given every few weeks rather than as several daily doses of supplements.
Disadvantages
- Given by injection rather than by mouth.
- Must not be combined with phosphate supplements or active vitamin D, which have to be stopped first.
- Needs regular phosphate blood tests to avoid levels rising too high.
Practical use
Good to know
The most important practical points are about what must not be combined with burosumab: oral phosphate supplements and active (so-called activated) forms of vitamin D should be stopped before starting it, because together they could raise phosphate to dangerous levels. Phosphate levels are checked regularly so the dose can be adjusted and high phosphate avoided, which also protects the kidneys. It is given as an injection under the skin every few weeks, and injection-site reactions are common but usually mild. It is started and supervised by a specialist team familiar with the condition. Tell your team about all your supplements and medicines so that anything affecting phosphate or vitamin D can be reviewed.
Who should not take it / use with caution
- It must not be used together with oral phosphate supplements or active (activated) vitamin D.
- It should not be started if the blood phosphate level is already in or above the normal range, until reviewed.
- It is used with caution in significant kidney problems and is not suitable for people who have had a serious allergic reaction to it.
Monitoring
- Regular blood phosphate levels to guide the dose and avoid levels rising too high.
- Checking kidney function and other bone-related blood tests over time.
- Reviewing bone symptoms, growth in children, and any dental problems.
Side effects
- Injection-site reactions such as redness, pain or itching, usually mild.
- Headache, tooth or jaw problems such as tooth abscesses, or muscle and joint aches.
- A rise in blood phosphate if not monitored, which is why regular blood tests are needed.
Key interactions
- Oral phosphate supplements and active vitamin D must not be taken with it, as together they can raise phosphate too high.
- Tell your team about any supplements, as some contain phosphate or vitamin D.
- Other medicines should be reviewed with your specialist, who manages the phosphate balance.
Available as: A solution for injection under the skin, given by a healthcare team.
Answers
Burosumab: frequently asked questions
What is burosumab used for?
It is used to treat X-linked hypophosphataemia, an inherited condition that causes low phosphate and weak bones, by blocking the hormone that makes the body lose phosphate.
Why must I stop phosphate and active vitamin D?
Taken together with burosumab, phosphate supplements and active vitamin D could push your phosphate dangerously high, so they are stopped before starting.
How is it given?
It is given as an injection under the skin every few weeks by your specialist team.
Why do I need regular blood tests?
Blood tests check your phosphate level so the dose can be adjusted to keep it in a safe range and protect your kidneys.
How is it different from the old treatment?
It treats the underlying cause of phosphate loss, whereas the older approach used phosphate supplements and active vitamin D, which burosumab replaces rather than adds to.
Authoritative sources
- BNF
- NICE CKS
Building a medicines information resource?
We create evidence-led, dose-free drug and formulary references for teams.