Vitamin D in a pediatric population after the end of home lockdown: a prospective study

Home confinement during the onset of the SARS-CoV-2 pandemic decreased sunlight exposure, the main source of vitamin D in the body. Objective: To evaluate the impact of SARS-CoV-2 confinement on 25-hydroxyvitamin D (25-OH-VD) levels in a pediatric population. Patients and Methods: Observational study in a Spanish pediatric population between June and October 2020. 25-OH VD levels were measured by electrochemiluminescence and several related variables were collected (anthropometry, sex, skin phototype, date, calcium level, inorganic phosphorus, parathormone, and alkaline phosphatase). The child's companion answered a survey that included the following aspects: access to open air in the house where the confinement took place, hours of sunlight per day received by the child after the end of the confinement, regular use of sunscreen with outdoor exposure, skin phototype of the child, type of milk the child usually drinks, 25-OH-VD supplementation intake, and if so, dosage and adherence to treatment. Results: 123 children participated, mean age 8.15 years (95%CI 7.52-8.79), and 56.1% were female. The median 25-OH-VD was 27.70 ng/ml (RIC 22.7533.60), and 14% presented 25-OH-VD insufficiency (< 20 ng/ml). 25-OH-VD levels presented an ascending correlation slope as the date moved away from the end of confinement (Rho 0.467; p < 0.001), being related to sunshine hours (Rho 0.368; p < 0.001). 25-OH-VD levels were higher in patients with photoprotection (median 29.9 vs 23.5 ng/ml, p = 0.005), with differences according to skin phototype (p = 0.032), but were not related to age, weight z-score, height z-score, body mass index z-score, or the presence of a balcony or garden at home. Conclusion: The rate of 25-OH-VD insufficiency at the end of confinement was not higher than in previous studies. 25-OH-VD levels increased progressively in relation to the hours of sunlight exposure and to the summer months. Interestingly, 25-OH-VD levels were higher in children using phot