Personal and Environmental Risk Factors at Birth and Hospital Admission: Direct and Vitamin D-Mediated Effects on Bronchiolitis Hospitalization in Italian Children

Relationships between 25-Hydroxyvitamin D Levels and Obstructive Sleep Apnea Severity in Children: An Observational Study

The prevalence of hypovitaminosis D is increasing worldwide. Vitamin D deficiency is supposed to play a role in sleep disturbances, but the complex relationships between hypovitaminosis D and pediatric obstructive sleep apnea syndrome (OSAS) are still incompletely understood. This study was aimed to retrospectively investigate the vitamin D status and significant clinical, laboratory, and instrumental variables in a cohort of pediatric patients with OSAS and to assess the possible relationship between serum vitamin D levels and OSAS severity. We consecutively enrolled all children aged 2-14 years admitted to our Pediatric Clinic from 1 July 2018 to 30 November 2020 for sleep-disordered breathing. Each patient underwent standard overnight in-hospital polygraphic evaluation, measurement of serum 25-hydroxyvitamin D (25(OH)D) levels, and clinical and laboratory investigation. A total of 127 children with OSAS were included. The 25(OH)D levels and BMI of OSAS patients were compared with those of an age-matched control group: the serum 25(OH)D levels were significantly lower in OSAS patients than in controls (22.4 vs. 25.5 ng/mL; p-value = 0.009), whereas no differences in the BMI percentile were found between the two groups. The mean value of 25(OH)D was not significantly lower (20.9 ng/mL) in the severe OSAS group compared with the mild (23.0 ng/mL) and moderate (23.3 ng/mL) OSAS groups (p-value = 0.28). Our findings indicate a relationship between vitamin D status and OSAS in children and suggest that severe cases of OSAS have lower vitamin D levels. Future, more extensive prospective studies are needed to confirm such preliminary findings.

Vitamin D and Healthcare Service Utilization in Children: Insights from a Machine Learning Approach

Vitamin D deficiency and insufficiency is a global health issue: an association has been demonstrated between vitamin D deficiency and a myriad of acute and chronic illnesses. Data regarding vitamin D status among children hospitalized with non-critical illnesses are scanty. We aimed to: (1) identify profiles of children hospitalized due to non-critical illnesses, using vitamin D levels as the driving outcome; (2) assess the association between patient profiles and length of stay. The study included 854 patients (1−17 years old) who underwent blood tests for detecting vitamin D levels. A regression tree was used to stratify patients. The relationship between vitamin D levels and length of stay was explored using Poisson regression. The regression tree identified three subgroups. Group A (16%): African, North African, Hispanic, and Indian patients. Group B (62%): Caucasian and Asian patients hospitalized for respiratory, metabolic, ill-defined, infective, and genitourinary diseases. Group C (22%): Caucasian and Asian patients hospitalized for digestive, nervous, and musculoskeletal diseases, blood and skin diseases, and injuries. Mean serum vitamin D level (ng/mL) was 13.7 (SD = 9.4) in Group A, 20.5 (10.0) in Group B, and 26.2 (12.6) in Group C. Group B was associated with the highest BMI z-score (p < 0.001) and the highest frequency of preterm births (p = 0.041). Mean length of stay was longer in Group A than in the other groups (p < 0.001) and decreased significantly by 9.8% (p = 0.024) in Group A and by 5% (p = 0.029) in Group B per 10 ng/mL increase in vitamin D level. We identified three subgroups of hospitalized children, defined according to ethnicity and discharge diagnosis, and characterized by increasing vitamin D levels. Vitamin D levels were associated with length of hospitalization.

Detection of Vitamin D Metabolites in Breast Milk: Perspectives and challenges for measurement by Liquid Chromatography Tandem-Mass Spectrometry

Breast milk is an emerging matrix for vitamin D assessment of breastfed infants and their mothers. It is considered a more reliable indicator of infant intake than the assessment of maternal circulating vitamin D. With the improved sensitivity of mass spectrometry-based technologies, this method principle has been the recent mainstay for the quantitation of various vitamin D metabolites in breast milk for population-based clinical trials. There are still several areas across the total testing process (pre-analytical, analytical and post-analytical) to be defined and harmonised to translate breast milk vitamin D measurement by liquid chromatography-tandem mass spectrometry (LC-MS/MS) from population-based research to routine clinical use and public health applications. Pre-analytically, the determination of the best form of vitamin D to measure in breast milk requires more evidence. Analytically, standardisation of the methods to allow for comparability of results is required. Post analytically, breast milk vitamin D decision limits are needed to turn the individual numerical outputs into clinically meaningful results. This review aims to synthesise the current evidence and utility of measurement of breast milk vitamin D by LC-MS/MS and to lead a future discussion on best practices to allow for its clinical utility beyond its current research-based use.