Researchers studied nearly 60,000 people with chronic kidney disease to understand how vitamin D deficiency affects kidney health. They found that people with low vitamin D levels were more than twice as likely to experience serious kidney complications within a year compared to those with normal vitamin D levels. The study also showed these patients had higher rates of hospitalization and death from all causes. This research suggests that checking and maintaining healthy vitamin D levels might be an important part of caring for people with kidney disease.

The Quick Take

  • What they studied: Whether people with kidney disease who have low vitamin D levels experience more serious kidney problems than those with normal vitamin D levels
  • Who participated: Nearly 60,000 adults with chronic kidney disease who had their vitamin D levels tested between 2010 and 2025. The groups were matched so they were similar in other ways besides vitamin D levels.
  • Key finding: People with low vitamin D were 2.24 times more likely to have serious kidney complications within one year. They also had higher rates of hospitalization and death from any cause.
  • What it means for you: If you have kidney disease, maintaining healthy vitamin D levels may help protect your kidneys and overall health. However, you should talk to your doctor before taking vitamin D supplements, as kidney disease patients need special care with certain nutrients.

The Research Details

This was a retrospective cohort study, which means researchers looked back at medical records of patients who already had their vitamin D tested. They used a large database called TriNetX that combines information from many hospitals and clinics across the world. The researchers divided patients into two groups: those with low vitamin D and those with normal vitamin D levels. To make sure the groups were fair to compare, they used a special statistical method called propensity score matching that balanced out other differences between the groups, like age and other health conditions. Then they followed both groups for one year to see who developed serious kidney problems.

This study design is strong because it uses real-world medical data from many different hospitals rather than just one location. By matching the groups carefully, the researchers could focus on the effect of vitamin D specifically, rather than other factors that might affect kidney health. Following patients for a full year gives enough time to see whether serious kidney problems develop.

The study included a very large number of patients (nearly 60,000 in each group), which makes the results more reliable. The researchers used proper statistical methods to ensure the groups were comparable. The findings were very consistent and statistically significant, meaning the results are unlikely to have happened by chance. However, because this study looked at past medical records rather than randomly assigning people to treatment groups, we cannot be completely certain that low vitamin D directly causes kidney problems, only that they are associated.

What the Results Show

The main finding was striking: people with vitamin D deficiency had a 2.24 times higher risk of experiencing major adverse kidney events compared to those with normal vitamin D levels. This means if 100 people with normal vitamin D had 10 serious kidney events, we would expect about 22 serious kidney events in 100 people with low vitamin D. This difference was very statistically significant, meaning it’s very unlikely to have happened by chance.

Beyond kidney-specific problems, the study found that people with low vitamin D also had higher rates of hospitalization for any reason and higher rates of death from any cause during the one-year follow-up period. These secondary findings suggest that vitamin D deficiency may affect overall health in people with kidney disease, not just kidney function.

The results were consistent across the large study population, with clear patterns showing that lower vitamin D levels were associated with worse outcomes. The researchers carefully controlled for other factors that might affect kidney health, making it more likely that vitamin D deficiency itself was contributing to the increased risk.

Beyond the primary kidney outcomes, the study found that patients with vitamin D deficiency had significantly higher rates of all-cause hospitalization, meaning they were admitted to the hospital more often for any health reason. Additionally, these patients had higher mortality rates, meaning more deaths occurred in the vitamin D deficiency group during the follow-up period. These findings suggest that vitamin D may play a broader role in overall health for people with kidney disease.

Previous research has suggested that vitamin D plays important roles in bone health, immune function, and inflammation control. This study adds to that evidence by showing a strong connection between vitamin D deficiency and serious kidney complications in people who already have kidney disease. The findings align with smaller studies that have suggested vitamin D is important for kidney health, but this is one of the largest studies to examine this relationship in a diverse population.

While this study is large and well-designed, it has some important limitations. Because researchers looked at past medical records rather than randomly assigning people to receive or not receive vitamin D, we cannot say for certain that low vitamin D causes kidney problems—only that they are associated. Other unmeasured factors could potentially explain the connection. Additionally, the study doesn’t tell us the best vitamin D levels for kidney disease patients or whether vitamin D supplements would actually help, since it only looked at people’s natural vitamin D levels. The results may not apply equally to all populations, as the study used data from a specific healthcare network.

The Bottom Line

If you have chronic kidney disease, ask your doctor to check your vitamin D level. If it’s low, discuss whether vitamin D supplementation is appropriate for you. Do not start taking vitamin D supplements on your own without medical guidance, as kidney disease patients need special care with nutrients. Your doctor may recommend specific doses based on your kidney function and other health factors. (Confidence level: Moderate—the association is clear, but we need more research to confirm that supplements help.)

This research is most relevant for people with chronic kidney disease, their doctors, and healthcare providers managing kidney disease. It’s also important for anyone with kidney disease who has symptoms of vitamin D deficiency like bone pain or weakness. People without kidney disease should not assume these findings apply to them, as kidney disease changes how the body handles vitamin D. If you have kidney disease, this gives you another reason to work closely with your healthcare team.

If you start vitamin D supplementation under medical supervision, it typically takes several weeks to months to build up vitamin D levels in your body. Improvements in kidney function or reduction in kidney complications would likely take several months to become apparent. This is not a quick fix but rather part of long-term kidney disease management.

Want to Apply This Research?

  • Track your vitamin D test results and levels quarterly (every 3 months) if you have kidney disease. Record the date, vitamin D level in ng/mL, and any supplements you’re taking. Note any changes in kidney function markers like creatinine or GFR if your doctor provides them.
  • If your doctor recommends vitamin D supplementation, set a daily reminder to take your supplement at the same time each day. Log each dose in your app to maintain consistency. Also track any symptoms like bone pain, muscle weakness, or fatigue that might improve with proper vitamin D levels.
  • Create a long-term tracking dashboard that shows your vitamin D levels over time alongside your kidney function markers. Set quarterly check-in reminders to review your levels with your doctor. If you’re supplementing, track whether your levels are improving and whether your kidney health markers are stable or improving. Share this data with your healthcare provider at each visit.

This research shows an association between vitamin D deficiency and serious kidney problems in people with chronic kidney disease, but it does not prove that low vitamin D directly causes these problems. If you have kidney disease, do not start taking vitamin D supplements without consulting your doctor first, as kidney disease patients have special nutritional needs and some supplements can be harmful. Always work with your healthcare team to manage your kidney disease and determine appropriate vitamin D levels for your specific situation. This information is for educational purposes and should not replace professional medical advice.