Vitamin D deficiency and associated factors among children in a tertiary care hospital setting: A retrospective cohort study.

Background: Vitamin D plays important roles in skeletal and extra-skeletal tissues. However, little is known about the vitamin D status in children in a hospital setting. We aimed to assess the vitamin D status, risk factors for vitamin D deficiency (VDD), and changes in biochemical profiles among children at a tertiary medical center in Taiwan.

Methods: This retrospective cohort study analyzed data from the Big Data Center of Taipei Veterans General Hospital. Children under 18-year-old who underwent 25-hydroxyvitamin D measurements between 2018 and 2023 were enrolled. Logistic regression analysis was performed to determine the risk factors for VDD.

Results: Among 1222 children enrolled, with a mean age of 8.5±5.4 years, 597 (48.9%) had VDD. VDD was significantly associated with female sex (odds ratio [OR] 1.624, 95% confidence interval [CI] 1.270-2.076), age >12 years (OR 2.479, 95% CI 1.584-3.881), vitamin D measurement during the spring/winter seasons (OR 1.716, 95% CI 1.340-2.197), and hospitalized children (OR 1.949, 95% CI 1.439-2.640). Age >1-6 years was a protective factor against VDD (OR 0.391, 95% CI 0.244-0.628). In addition, the OR of VDD was higher in those with an elevated intact parathyroid hormone level (OR 8.667, 95% CI 1.338-56.157).

Conclusion: Despite the high sun exposure in Taiwan, VDD is prevalent among children and adolescents. Physicians should be aware of VDD, especially in children who are female, aged >12 years, hospitalized, have increased intact parathyroid hormone levels, and during the spring/winter.