Researchers in Romania studied whether testing children for vitamin D deficiency actually helps catch the problem early. They looked at nearly 3,600 children over seven years, including during the COVID-19 pandemic when fewer kids went to the hospital. They found that vitamin D deficiency is common in children and that testing about 17% of admitted children was the best way to find cases without wasting resources. The study shows that older children are more likely to have low vitamin D levels, and that having a smart testing program helps doctors catch and treat this problem before it affects bones and immune health.

The Quick Take

  • What they studied: Whether Romania’s program to test children for vitamin D deficiency actually works at finding kids who need help, especially during the COVID-19 pandemic
  • Who participated: 3,596 children (ages 0-18) who were admitted to a children’s hospital in Romania between 2018 and 2024. About 54% were boys, and the average age was about 5 years old
  • Key finding: The testing program successfully found more vitamin D deficiency cases over time (increasing from 12.6% to 17.5% of tested children). Older children were more likely to have low vitamin D levels, with each year of age increasing the risk by about 8-9%
  • What it means for you: If you have children, especially older ones, vitamin D testing might be worth discussing with your doctor. The study suggests that smart, targeted testing programs can help catch vitamin D problems early without testing every single child

The Research Details

This was a retrospective observational study, which means researchers looked back at medical records from children who had already been tested and admitted to a hospital in Timișoara, Romania. They examined blood test results for vitamin D levels from January 2018 through December 2024, covering the period before, during, and after the COVID-19 pandemic.

The researchers included children ages 0-18 who had at least one hospital admission and a vitamin D test. They excluded children in intensive care units, those having surgery, non-Romanian citizens, and children with life-threatening conditions. This approach allowed them to study how the hospital’s vitamin D screening program worked in real-world conditions.

The team used statistical analysis to identify patterns in vitamin D deficiency and determine which factors (like age or time period) made deficiency more likely. They also calculated the best percentage of children to test to catch cases efficiently without wasting resources.

This type of study is important because it shows whether a real-world health program actually works. Rather than testing every child (which costs too much money), the researchers wanted to know if testing only certain children could still catch vitamin D problems effectively. This information helps hospitals and doctors in countries with limited budgets decide how to use their resources wisely.

The study examined a large number of children (3,596) over a long time period (7 years), which makes the findings more reliable. The researchers also looked at how the pandemic affected testing and hospital visits, showing they considered real-world factors. However, the study only included children who came to one hospital, so results might be different in other places. The study was observational rather than experimental, meaning researchers couldn’t control all the factors that might affect vitamin D levels.

What the Results Show

The National Vitamin D Screening Programme successfully increased detection of vitamin D deficiency in children over the study period. The percentage of children found to have insufficient vitamin D rose from 12.6% to 17.5% as the program improved and more children were tested.

Age was the strongest predictor of vitamin D deficiency. For every year older a child was, their chances of having low vitamin D increased by 8-9%. This means teenagers were much more likely to have vitamin D deficiency than toddlers.

The COVID-19 pandemic significantly disrupted the program. Hospital admissions dropped dramatically during 2020-2022 (averaging 2,057 admissions per year) compared to before and after the pandemic (averaging 4,045 admissions per year). Despite these disruptions, the program continued to identify vitamin D deficiency cases.

The researchers found that testing approximately 17% of admitted children represented the optimal balance—catching enough cases to help children while not wasting resources on unnecessary testing.

The study revealed that vitamin D deficiency remained a persistent problem throughout the entire seven-year period, even as awareness and testing improved. The pandemic’s impact on hospital visits meant fewer children were screened during 2020-2022, but when testing resumed at higher rates, more deficiency cases were detected. This suggests that the deficiency problem was likely larger than initially detected during the pandemic years.

This research aligns with previous studies showing that vitamin D deficiency is common in children, particularly in Europe and in countries with limited sunlight exposure. The finding that older children have higher deficiency rates matches what other researchers have observed. The study adds new information by showing that a targeted screening program (testing selected children rather than all children) can be effective and practical for hospitals with limited resources.

The study only included children admitted to one hospital in Romania, so the results might not apply to all children in Romania or other countries. Children who were very sick, in intensive care, or having surgery were excluded, so the findings don’t tell us about vitamin D deficiency in those groups. The study looked at past records rather than following children forward in time, which limits what we can learn about how vitamin D deficiency affects children’s health over time. Additionally, the study didn’t examine why vitamin D deficiency occurs or what factors in children’s daily lives (like sun exposure, diet, or skin tone) might contribute to it.

The Bottom Line

Based on this research, doctors may want to consider vitamin D testing for children, especially those over age 5, as part of routine hospital care. Parents might discuss vitamin D screening with their pediatrician, particularly if their child has risk factors for deficiency. The evidence suggests that targeted testing (rather than testing every child) is an effective approach. Confidence level: Moderate—the study shows the program works, but more research is needed to determine the best testing strategy for all children.

Parents of children, especially those ages 5-18, should be aware of vitamin D deficiency as a potential health concern. Healthcare providers and hospital administrators in countries with limited healthcare budgets should pay attention to this research, as it shows an efficient testing approach. Children with limited sun exposure, dietary restrictions, or certain medical conditions may benefit most from vitamin D screening. This research is particularly relevant for developing countries seeking cost-effective health screening programs.

Vitamin D deficiency doesn’t cause immediate symptoms, so benefits from treatment develop gradually over weeks to months. Bone health improvements and immune system benefits typically become apparent after consistent vitamin D supplementation for 2-3 months. If a child is found to have deficiency through screening, treatment should begin promptly, but patience is needed to see full benefits.

Want to Apply This Research?

  • Track your child’s vitamin D test results and supplementation dates. Record the serum 25-hydroxyvitamin D level (measured in ng/mL or nmol/L) at each test, along with the date and any supplements started. Set reminders for follow-up testing as recommended by your doctor (typically 2-3 months after starting supplementation).
  • If your child is found to have vitamin D deficiency, use the app to: (1) set daily reminders to take vitamin D supplements, (2) log outdoor time and sun exposure, (3) track dietary sources of vitamin D (fatty fish, fortified milk, egg yolks), and (4) record any symptoms that might improve with treatment.
  • Create a long-term tracking system that records vitamin D test results annually or as recommended by your doctor. Use the app to monitor trends over time and identify seasonal patterns (vitamin D levels often drop in winter). Share this data with your healthcare provider during check-ups to adjust supplementation as needed.

This research describes a screening program’s effectiveness but does not provide medical advice. Vitamin D testing and supplementation decisions should be made with your child’s pediatrician or healthcare provider, who can assess your child’s individual risk factors, dietary intake, sun exposure, and medical history. Do not start or stop vitamin D supplements without consulting your doctor. This study was conducted in Romania and may not apply to all populations or healthcare settings. If you have concerns about your child’s vitamin D status, speak with a qualified healthcare professional.