The Association Between Vitamin D Levels and Infections in Patients with Primary Immunodeficiency

Introduction: Vitamin D is a hormone responsible in the regulation of immune response. This study was designed to assess the relationship of vitamin D deficiency on the development of infections in patients with primary immunodeficiency (PID). Materials and Methods: A total of 39 patients (M/F: 23/16) and 39 age-and sex-matched healthy controls (M/F: 23/16) were enrolled in the study. We measured the frequency of infections and serum vitamin D levels in winter and summer seasons. Results: The median age of the patient and control groups were 15.0 (Interquartile range: 7.5-26.0) years and 14.0 (9.0-25.0) years, respectively (P=0.810). Winter and summer vitamin D levels were similar both in patient and control groups (p=0.492 for winter, p=0.503 for summer). Number of the patients with low serum vitamin D levels and with infections were higher in winter than in summer. Auroimmune and inflammatory diseases (AID) were predominantly observed in patients with low winter vitamin D levels and in common variable immunodeficiency (CVID) group. Patients with CVID had lower serum vitamin D levels both in summer (p=0.048) and in winter (p=0.008). Conclusions: In this study, we showed the seasonal variation of serum vitamin D in patients with PID. There was also increased frequency of CVID and AID in those patients with low vitamin D levels. In addition, vitamin D might be given in winter to the patients with PID to rake infections and autoimmune disorders under control.