Exploring the relationship between serum 25-hydroxyvitamin D levels and allergic rhinitis severity in the pediatric...

Recent studies have suggested that serum 25-hydroxyvitamin D₃ (s25-OHD₃) may modulate immune responses in allergic diseases. However, the relationship between s25-OHD₃ levels, allergic rhinitis (AR) severity, and allergen sensitization remains unclear. This study aimed to investigate the association between s25-OHD₃ levels and AR severity, including the potential role of allergen sensitization.

This retrospective study, conducted at Ankara Bilkent City Hospital between 2019 and 2024, included 343 children with AR aged 2 to 18 years. Patients were evaluated for s25-OHD₃ levels, allergen sensitization (via skin prick test and/or serum-specific IgE), and clinical characteristics. AR severity was classified according to Allergic Rhinitis and its Impact on Asthma (ARIA) guidelines, and clinical response to vitamin D supplementation was reassessed after 12 weeks. Risk factors for increased AR severity were identified by regression analysis.

The median s25-OHD₃ level was 16.0 ng/mL (IQR: 10.8-22.0). An inverse correlation was observed between age and s25-OHD₃ levels (r_s = -0.202, p < 0.001). Lower s25-OHD₃ levels were significantly associated with greater AR severity (p < 0.001). Additionally, patients with concomitant allergic diseases - particularly those with allergic conjunctivitis, asthma, and atopic dermatitis - had significantly lower s25-OHD₃ levels (p = 0.004, p = 0.032, and p = 0.042, respectively). Notably, sensitization to cat dander was also associated with reduced s25-OHD₃ levels (p = 0.043). Multivariable regression analysis identified lower s25-OHD₃ levels, coexisting allergic conjunctivitis, pollen sensitization, and polysensitization as independent risk factors associated with increased AR severity. Furthermore, a significant reduction in AR severity was observed following vitamin D supplementation (p < 0.001).

This study underscores the impact of s25-OHD₃ deficiency on the severity of AR and highlights the importance of evaluating s25-OHD₃ levels in the management of pediatric AR to support the development of targeted therapeutic approaches.