Evaluation of the Effects of Age Group, Gender and Seasonal Factors on Vitamin D Levels in 9496 Children

Aim: This study aimed to evaluate vitamin D levels, which were determined over a year in the pediatric
clinic of a training and research hospital in Central Anatolia, according to age groups, gender, and
seasonal characteristics.
Patients and Methods: This retrospective study was conducted using the data of children aged 0–18
years who applied to the children’s clinic of a hospital between January 2019 and December 2019 and
whose vitamin D levels were determined. Children were divided into five different age groups, 28 days–12
months, 13 months–2 years, 2–5 years, 6–11 years, and 12–18 years, in accordance with Standard 6
recommendations. Vitamin D levels were evaluated in terms of age group, gender, and admission season.
Results: A total of 9496 children, 5360 (56.4%) females and 4136 (43.6%) males, were included in the
study. A 25(OH)D level below 20 ng/mL (representing a deficiency) was found in 6472 (68.2%) of the
participants, while 2085 (21.9%) participants had a 25(OH)D level between 21–29 ng/mL (representing an
insufficiency) and 939 (9.9%) participants had a 25(OH)D level over 30 ng/mL (representing sufficiency).
It was determined that vitamin D levels are lower in girls than in boys, vitamin D levels are inversely
proportional to age, and vitamin D levels reach their lowest values in winter and highest values in summer.
The effects of age group, gender, and season of admission on vitamin D levels were statistically significant
(P < 0.001).
Conclusion: The mean vitamin D levels for all age groups were either insufficient or deficient. Vitamin D
levels in children aged 0–18 is related to age, gender, and season. Necessary measures should be taken,
especially for at-risk groups, to prevent vitamin D deficiency or insuf ficiency.