Vitamin D as a predictor of severe course of inflammatory bowel diseases in children
Authors: Sorokman T.V. , Sokolnyk S.V. , Popelyuk N.O. , Makarova O.V. 
Published: January 2024

Background. Inflammatory bowel diseases (IBD) develop in childhood more often, last throughout life, and their frequency is rapidly increasing in industrialized countries. Most researchers identify vitamin D (VD) as a key regulator of gastrointestinal homeostasis, an innate immune response and a biomarker for the activity and severity of IBD. The purpose was to determine the frequency of vitamin D deficiency and its relationship with the course of inflammatory bowel diseases in children. Materials and methods. The study included 36 patients: 13 with IBD (main group) and 23 children of the comparison group with irritable bowel syndrome and functional abdominal pain. The average age of children was 13.09 ± 2.28 years, with a median of 14.5 years; 63.6 % were boys. Patients with IBD were evaluated for clinical disease manifestations, disease localization (Paris Classification) and disease activity (PCDAI/PUCAI). Irritable bowel syndrome and functional abdominal pain were diagnosed based on the Rome IV Criteria. Serum 25-hydroxyvitamin D (25(OH)D) was assessed by the electrochemiluminescence method (Elecsys Vitamin D total, Cobas). Results. Severe IBD prevailed among the examined children (61.5  %). There was no significant difference in overall body weight and height between the groups, which may be due to the short duration of IBD. However, children with IBD showed a tendency to lower physical development indicators. Significant differences in hemoglobin, erythrocyte sedimentation rate, C-reactive protein, number of platelets, fecal calprotectin were observed among the studied groups (p < 0.05). The concentration of VD in the blood of the examined children ranged from 39.9 to 10.8 ng/ml, with an average of 21.8 ± 5.8 ng/ml. In 76.9 % of patients with IBD, blood concentration of VD reduced, while only 21.7 % children in the comparison group had its level below the norm. Children with IBD were characterized by significantly lower levels of VD in the blood (average of 16.7 ng/ml). Lower levels of VD were associated with female sex, Chron’s disease (CD) and ulcerative colitis (UC), as well as disease duration of more than 3 years and disease severity. There was an inverse correlation between VD and the degree of IBD activity (CD: r = –0.33; p = 0.01; UC: r = –0.38; p = 0.01) and the severity of the course (CD: r = –0.35; p = 0.01; UC: r = –0.36; p = 0.01), the levels of C-reactive protein (CD: r = –0.39; p = 0.01; UC: r = –0.37; p = 0.01) and fecal calprotectin (CD: r = –0.42; p = 0.01; UC: r = –0.46; p = 0.01). Conclusions. In most children (76.9 %) with inflammatory bowel diseases, the concentration of VD in the blood is significantly lower than in those with functional gastrointestinal disorders. Lower vitamin D levels were associated with female sex, Crohn’s disease, and ulcerative colitis, as well as disease duration of more than 3 years, activity level, and severity, supporting the role of vitamin D as a possible predictor of severity of these diseases in childhood.