Abstract:Objective To study the effects of alfacalcidol on serum 25-(OH)D3 level, cellular immune function, and inflammatory factors in children with Henoch-Sch?nlein purpura (HSP). Methods A total of 200 children with HSP were prospectively enrolled from June 2018 to June 2020. According to the random number table method, they were divided into an observation group and a control group (n=100 each). The control group was treated with vitamin C, rutin tablets, dipyridamole, cimetidine, calcium supplements, and glucocorticoids. In addition to the treatment for the control group, the observation group received alfacalcidol capsules (0.25 μg/d) orally before bed for 4 weeks. The two groups were compared in terms of the level of 25-(OH)D3, the percentages of T lymphocyte subsets (CD3+, CD4+, and CD8+) and NK cells, and the levels of inflammatory factors, interleukin-6 (IL-6), interleukin-17 (IL-17), interleukin-21 (IL-21), and tumor necrosis factor-α (TNF-α), before treatment and after 4 weeks of treatment. The children were followed up for 6 months to determine the recurrence rate and the incidence of renal damage. Results After treatment, the observation group showed a significantly higher serum 25-(OH)D3 level, significantly higher percentages of CD3+T cells, CD4+T cells, and NK cells, and significantly lower levels of IL-6, IL-17, IL-21, and TNF-α compared with the control group (P<0.05). After 6 months of follow-up, the recurrence rate and the incidence of renal damage in the observation group were significantly lower than those in the control group (P<0.05). Conclusions Alfacalcidol can increase the serum 25-(OH)D3 level, improve cellular immune function, decrease inflammatory factor levels, and reduce recurrence and renal damage in children with HSP.