Researchers studied vitamin D levels in children and teens who had broken bones. They found that kids with fractures above the ankle (like thigh or shin breaks) had much lower vitamin D levels than those with arm fractures or ankle/foot breaks. More than half of the kids with leg fractures didn’t have enough vitamin D in their blood. This matters because vitamin D helps bones stay strong and heal properly. The study suggests doctors should check vitamin D levels in all children who break bones, especially those with serious leg injuries.

The Quick Take

  • What they studied: Whether children with broken bones in different body parts have different levels of vitamin D in their blood
  • Who participated: 156 children and teenagers (ages 3-18) who came to the hospital with broken arms, legs, or ankles between October 2021 and April 2025
  • Key finding: Kids with leg fractures above the ankle had vitamin D levels of 18.9 ng/mL, which was significantly lower than kids with arm fractures (25.7 ng/mL) or ankle/foot fractures (23.7 ng/mL). About 58% of kids with leg fractures had vitamin D deficiency, compared to only 30% in the other groups.
  • What it means for you: If your child breaks a leg, doctors should test their vitamin D levels. Low vitamin D might affect how well bones heal. This is especially important for kids with serious leg fractures that need surgery.

The Research Details

This was a prospective study, meaning researchers followed children forward in time as they came to the hospital with broken bones. When kids arrived with fractures, doctors ordered a blood test to measure their vitamin D levels. The researchers divided the children into three groups based on where they broke their bones: upper extremity (arms), lower extremity above ankle (thighs and shins), and ankle/foot fractures.

The study included children ages 3 to 18 with arm or leg fractures. They excluded children with certain types of fractures (like spine or pelvis breaks) or those with special bone or muscle disorders. This helped ensure the results were about vitamin D and fracture location, not other medical conditions.

The researchers compared vitamin D levels between the three fracture groups and also looked at whether vitamin D levels were different in kids who needed surgery versus those who didn’t.

By comparing vitamin D levels across different fracture locations, researchers could see if certain types of fractures are linked to lower vitamin D. This approach is stronger than just comparing kids with fractures to healthy kids, because it shows whether the fracture location itself matters. Understanding these patterns helps doctors know which patients need vitamin D testing and treatment.

This study followed real patients as they came to the hospital (prospective design), which is more reliable than asking people to remember past events. The sample size of 156 patients is reasonable for this type of research. The study was approved by an ethics board before it started. However, the study only looked at one hospital system, so results might be different in other places. The researchers didn’t randomly assign kids to groups—they studied kids who already had fractures—so we can’t prove vitamin D causes fractures, only that they’re connected.

What the Results Show

The main finding was clear: children with leg fractures above the ankle had much lower vitamin D levels than the other two groups. Their average vitamin D level was 18.9 ng/mL, compared to 25.7 ng/mL in kids with arm fractures and 23.7 ng/mL in kids with ankle/foot fractures. These differences were statistically significant, meaning they’re very unlikely to have happened by chance.

When researchers looked at vitamin D deficiency (defined as less than 20 ng/mL), the pattern was striking. About 58% of kids with leg fractures above the ankle had deficiency, compared to only 30% in both the arm fracture group and ankle/foot fracture group. This means more than half of the kids with serious leg breaks didn’t have enough vitamin D.

On the flip side, when looking at kids with healthy vitamin D levels (30 ng/mL or higher), only 8% of the leg fracture group had sufficient levels. In contrast, 31% of the arm fracture group and 23% of the ankle/foot group had sufficient vitamin D. This shows that kids with leg fractures were much less likely to have healthy vitamin D levels.

When researchers looked at whether surgery made a difference, they found that kids who needed surgery had slightly lower vitamin D overall (21.4 ng/mL) compared to kids who didn’t need surgery (24.7 ng/mL). However, within each fracture group separately, surgery versus no surgery didn’t make a significant difference in vitamin D levels.

An interesting pattern emerged when looking at treatment type. Kids with arm fractures were more likely to be treated without surgery (58% didn’t need surgery), and these kids had higher vitamin D levels. In contrast, kids with leg fractures above the ankle were more likely to need surgery (81% required surgery), and these kids had lower vitamin D levels. This suggests that the type of fracture itself—not just whether surgery was needed—is what’s connected to vitamin D levels.

Previous studies on this topic had mixed results, with some showing vitamin D was linked to fracture risk and others not finding clear connections. This study helps clarify things by showing that the location of the fracture matters. The finding that at least 30% of all kids with fractures have vitamin D deficiency supports recommendations from other researchers that all children with broken bones should have their vitamin D tested.

This study only looked at one hospital system, so results might be different in other areas or countries with different climates and sun exposure. The study couldn’t prove that low vitamin D causes fractures—only that they’re connected. It’s possible that kids with leg fractures have lower vitamin D for other reasons, or that low vitamin D and fractures are both caused by something else (like less outdoor activity). The study didn’t track whether kids’ vitamin D levels improved and whether that helped them heal better. Finally, the study was published in December 2025, so it’s very recent and other researchers haven’t had time to confirm these findings yet.

The Bottom Line

Based on this research, doctors should test vitamin D levels in all children who break bones, especially those with leg fractures above the ankle. If a child has low vitamin D, doctors should consider recommending vitamin D supplements or increased sun exposure and dietary sources of vitamin D. The evidence for this recommendation is moderate—it’s based on one study showing a clear connection, but more research is needed to confirm it helps kids heal better.

Parents of children who have broken bones should care about this, especially if the break is in the leg above the ankle. Kids who spend little time outdoors, live in northern climates with less sun, or have dietary restrictions might be at higher risk for low vitamin D. Children with multiple fractures or fractures that need surgery should definitely have vitamin D checked. This is less relevant for kids with arm fractures or ankle/foot fractures, which showed higher vitamin D levels in this study.

If a child is found to have low vitamin D after a fracture, it typically takes 4-8 weeks of supplementation to bring levels back to normal. Improved vitamin D levels might help with bone healing, but this study didn’t measure how long healing took, so we don’t know exactly how much faster bones might heal with better vitamin D.

Want to Apply This Research?

  • If your child has a fracture, track their vitamin D level at the time of injury and then again 6-8 weeks after starting supplementation. Record the specific numbers (in ng/mL) to see if they’re moving toward the healthy range of 30 ng/mL or higher.
  • Use the app to set reminders for daily vitamin D supplements if prescribed by a doctor. Also track sun exposure time (aim for 10-30 minutes daily depending on skin type and location) and vitamin D-rich foods eaten (like fortified milk, fatty fish, and egg yolks). Set a goal to reach vitamin D sufficiency by the time of the next doctor’s visit.
  • Create a long-term tracking system that monitors vitamin D levels at fracture diagnosis, at 6-8 weeks, and at 3 months. Also track bone healing progress (pain levels, return to activity, doctor’s assessment) to see if improved vitamin D correlates with better healing outcomes. This personal data can help your child’s doctor make better treatment decisions.

This research shows an association between low vitamin D and leg fractures in children, but does not prove that low vitamin D causes fractures. This information is for educational purposes and should not replace professional medical advice. If your child has a fracture, consult with their doctor about whether vitamin D testing and supplementation are appropriate. Do not start any supplements without talking to your child’s healthcare provider first, as vitamin D supplementation should be personalized based on your child’s individual health status, diet, sun exposure, and any other medical conditions. This study was conducted at one hospital system and results may vary in different populations.