The comparisons of vitamin D3 levels in IgA vasculitis across different subgroups and healthy children: a comparative study.

Background: IgA vasculitis is the most common form of vasculitis in children. Vitamin D deficiency has been observed to contribute to immune function and the pathogenesis of various immune diseases. However, at present, only a few studies with small sample sizes have shown that IgA vasculitis patients have lower vitamin D levels than healthy children. Thus, we conduct a large study to investigate the significance of serum 25-hydroxyvitamin D3 (25(OH)D) levels of children with IgA vasculitis across different subgroups and healthy children. Methods: In this retrospective study, 1,063 children were recruited from the Ningbo Women and Children's Hospital between February 2017 and October 2019, including 663 patients hospitalized with IgA vasculitis and 400 healthy examination children who served as the control group at the same time. There wasn't any bias in the season. The healthy group came from children who underwent normal physical examination. The 663 IgA vasculitis patients were then divided into the IgA vasculitis-nephritis and non-IgA vasculitis-nephritis groups, streptococcal-infection and no-streptococcal-infection groups, gastrointestinal-involvement and no-gastrointestinal-involvement groups, and joint-involvement and no-joint-involvement groups. The serum 25(OH)D levels at disease onset were analyzed. All the participants were followed up for 6 months from the date of onset. Results: The serum 25(OH)D levels of the IgA vasculitis group (15.47±6.58 ng/mL) were significantly lower than those of the healthy control group (22.48±6.24 ng/mL) (P<0.01). There were no significant differences in terms of age and sex between the IgA vasculitis and healthy control group. Further, among the IgA vasculitis patients serum 25(OH)D levels were reduced in the IgA vasculitis-nephritis (12.99±4.92 ng/mL), streptococcal-infection (14.2±6.06 ng/mL), and gastrointestinal-involvement (14.43±6.33 ng/mL) groups (P=0.00, 0.004, 0.002, respectively). The vitamin D levels with IgA vasculitis were significantly lower in winter and spring than summer and autumn. Conversely, the joint-involvement group did not show a significant reduction in vitamin D levels compared to no joints involved group. Conclusions: IgA vasculitis patients have reduced vitamin D levels, which suggests that vitamin D deficiency may be involved in the development of IgA vasculitis. Vitamin D supplementation may reduce the incidence of IgA vasculitis, and maintaining high vitamin D levels in IgA vasculitis patients may prevent renal damage.