A five-year study of 340 children taking burosumab for X-linked hypophosphataemia found the medicine to be safe, with no serious problems directly caused by treatment and no children needing to stop the drug due to side effects. According to Gram Research analysis, 37.4% of children experienced at least one side effect, but only 14.4% had effects possibly related to the medicine itself, and no deaths occurred in either the burosumab or comparison groups.
Researchers studied a new medicine called burosumab that helps children with a rare genetic bone disease called X-linked hypophosphataemia (XLH). This condition makes bones and teeth weak and brittle. Scientists tracked 340 children taking burosumab and 91 children taking older treatments to see if the new drug was safe. After five years, burosumab proved to be safe with no serious problems directly caused by the medicine. The findings show that this newer treatment option works well for kids with this rare disease, though doctors still need to watch for certain side effects.
Key Statistics
A five-year safety study of 340 children published in the European Journal of Endocrinology in 2026 found that burosumab caused no serious adverse events directly related to treatment, with zero treatment-related withdrawals and zero deaths.
Among 340 children taking burosumab for X-linked hypophosphataemia, only 14.4% (49 children) experienced side effects that doctors considered possibly or probably caused by the medicine, according to a 2026 interim analysis.
In a 2026 study comparing burosumab to older treatments for rare bone disease in children, 37.4% of the burosumab group experienced any adverse event compared to 22% in the phosphate/vitamin D group, but serious complications were rare in both groups.
A 2026 five-year safety analysis found that serious complications like high phosphate levels and abnormal bone mineralization were rare in both children taking burosumab (340 participants) and those receiving older treatments (91 participants).
The Quick Take
- What they studied: Whether a new medicine called burosumab is safe for children and teenagers with X-linked hypophosphataemia, a rare genetic disease that weakens bones and teeth
- Who participated: 340 children and teenagers who received burosumab and 91 who received older treatments (phosphate supplements and/or vitamin D) for the same condition
- Key finding: According to Gram Research analysis, 37.4% of children taking burosumab experienced at least one side effect, compared to 22% taking older treatments, but no serious problems were directly caused by the new medicine
- What it means for you: If your child has this rare bone disease, burosumab appears to be a safe treatment option. However, doctors should still monitor for potential side effects, and this medicine is only for people with this specific genetic condition
The Research Details
This was a long-term safety study that followed children and teenagers with X-linked hypophosphataemia over five years. Researchers collected information from 340 children who took burosumab (the new medicine) and compared them to 91 children who took older treatments like phosphate supplements and vitamin D. The study tracked what side effects occurred, how serious they were, and whether any problems were directly caused by the medicine.
The researchers looked at data from hospitals and clinics around the world that treat this rare disease. They recorded everything about the children’s health, including any medical problems that happened during treatment. This approach is called a ‘post-authorisation safety study,’ which means it happened after the medicine was officially approved by health authorities.
The study was designed to answer an important question: since this disease is so rare, we need to make sure the new treatment is truly safe when used in real-world situations with many different children, not just the small groups tested before approval.
Rare diseases like XLH affect very few people, which makes it hard to test new medicines thoroughly before approval. This long-term study of 340 children provides important real-world safety information that doctors need to confidently prescribe burosumab. By comparing it to older treatments, researchers could see if the new medicine causes different or worse side effects.
This study is reliable because it tracked a large group of children (340) over a long time period (5 years) and compared them to a control group. The data came from many different hospitals and clinics worldwide, making the results more representative of real patients. However, the older treatment group was smaller (91 children), which makes that comparison less certain. The study was conducted by real-world medical centers rather than controlled laboratory settings, which makes the findings more applicable to everyday medical practice.
What the Results Show
The safety analysis showed that burosumab was well-tolerated in children and teenagers. Among the 340 children taking burosumab, 37.4% experienced at least one side effect during the five-year study. In comparison, 22% of the 91 children taking older treatments experienced side effects. However, only 49 children (14.4%) had side effects that doctors thought were possibly or probably caused by burosumab itself.
Most importantly, no child had to stop taking burosumab because of side effects, and there were no deaths in either group. No serious medical problems were directly caused by the medicine in either the burosumab group or the older treatment group. This means that while some children experienced health issues during the study, these problems were not caused by the medicine itself.
The study also looked for specific complications that doctors worry about with this type of treatment. Rare but serious problems like too much phosphate in the blood, high parathyroid hormone levels, and abnormal bone hardening in soft tissues were uncommon in both groups. The safety profile remained consistent throughout the five-year period, meaning the medicine did not become more dangerous over time.
Hospitalizations occurred in approximately 71% of participants in both groups, but these hospital visits were not directly related to the treatment itself. The similar hospitalization rates between burosumab and older treatment groups suggest that the new medicine does not increase the need for hospital care. The study found that side effects occurred at similar rates in younger children and older teenagers, indicating that burosumab appears equally safe across different age groups in the pediatric population.
These findings are consistent with earlier studies of burosumab in smaller groups of children. The safety profile observed in this large, five-year study confirms what researchers saw in earlier trials. No new or unexpected safety concerns emerged, which is reassuring for doctors and families considering this treatment. The results support the idea that burosumab is a reliable treatment option for this rare disease.
The study had some limitations worth noting. The group taking older treatments was much smaller (91 children) compared to the burosumab group (340 children), which makes direct comparisons less reliable. The study relied on data collected at different hospitals and clinics with potentially different record-keeping practices. Because this is a rare disease, the total number of children studied is still relatively small compared to studies of common diseases. Finally, the study was observational, meaning researchers watched what happened rather than randomly assigning children to different treatments, so we cannot be completely certain that differences between groups were caused by the medicine itself.
The Bottom Line
Burosumab appears to be a safe treatment option for children and teenagers with X-linked hypophosphataemia (Strong confidence based on 340 children followed for 5 years). Doctors should continue monitoring children taking this medicine for potential side effects, particularly watching for changes in phosphate and parathyroid hormone levels (Moderate confidence). Older treatments like phosphate supplements and vitamin D remain reasonable options, especially since they have longer safety records (Moderate confidence). Families should discuss with their doctor which treatment is best for their child’s specific situation.
This research is most relevant for children and teenagers diagnosed with X-linked hypophosphataemia and their families. Doctors who treat this rare disease should use these findings when discussing treatment options with patients. Genetic counselors and pediatric specialists will find this information helpful when recommending burosumab. This study does not apply to people without this specific genetic condition, as burosumab is only approved for XLH treatment.
Safety benefits and risks may become apparent within the first few months of treatment, but the full picture of long-term safety requires monitoring over years. Based on this five-year study, families should expect to have regular check-ups with blood tests to monitor phosphate and parathyroid hormone levels. Most side effects, if they occur, appear early in treatment rather than developing after years of use.
Frequently Asked Questions
Is burosumab safe for children with X-linked hypophosphataemia?
Research shows burosumab is safe for children with this rare bone disease. A five-year study of 340 children found no serious problems directly caused by the medicine, with no treatment-related deaths or forced treatment stops due to side effects.
What side effects do children experience when taking burosumab?
About 37.4% of children taking burosumab experienced some side effect during the study, but only 14.4% had effects possibly caused by the medicine itself. Serious complications like high phosphate levels were rare in both burosumab and older treatment groups.
How does burosumab compare to older treatments for X-linked hypophosphataemia?
Burosumab had a similar safety profile to older treatments like phosphate supplements and vitamin D. While slightly more children taking burosumab reported any side effect (37.4% vs 22%), no serious treatment-related problems occurred in either group.
How long do children need to take burosumab for this bone disease?
This study followed children for five years and found the medicine remained safe throughout that period. Long-term treatment appears necessary since X-linked hypophosphataemia is a lifelong genetic condition, but your doctor will determine the best duration for your child.
What should doctors monitor while children take burosumab?
Doctors should regularly check blood phosphate and parathyroid hormone levels, as the study identified these as potential areas of concern. Regular clinic visits with blood tests every 3-6 months help catch any rare complications early.
Want to Apply This Research?
- Track monthly blood phosphate and parathyroid hormone levels using the app’s lab result logging feature to monitor for the rare complications the study identified (hyperphosphataemia and elevated parathyroid hormone)
- Set reminders for regular clinic visits and blood work appointments every 3-6 months, and log any new symptoms or side effects immediately to share with your doctor at the next visit
- Create a long-term health dashboard showing trends in phosphate levels, parathyroid hormone, and bone health markers over months and years to identify any patterns or emerging concerns early
This article summarizes research findings and should not replace professional medical advice. X-linked hypophosphataemia is a rare genetic disease that requires specialized medical care. If your child has been diagnosed with XLH or you suspect they may have this condition, consult with a pediatric endocrinologist or geneticist. Treatment decisions should be made in consultation with qualified healthcare providers who can evaluate your child’s individual circumstances. This study provides safety information for burosumab but does not constitute a recommendation for or against any specific treatment. Always discuss potential benefits and risks of any medication with your child’s doctor before starting treatment.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.