Low vitamin D levels and frequencies of regulatory T cells (Tregs) are associated with adenotonsillar hypertrophy in children.

Objective: To evaluate the levels of vitamin D and the frequencies of regulatory T cells (%Tregs) in children undergoing adenotonsillectomies (T&As) and their controls.

Methods: We prospectively collected data from 130 children aged from 2 to 14 years old undergoing T&As and 60 undergoing unrelated elective procedures from November 1, 2015 to December 20, 2017 at the First Affiliated Hospital of Anhui Medical University. Demographic and disease specific data was obtained in addition to blood samples for the measurement of 25-hydroxy (OH)-vitamin D, interleukin-10 and %Tregs.

Results: Among the 130 patients undergoing T&As who had 25(OH) vitamin D levels measured, 40.8% were vitamin D deficient (25(OH) vitamin D < 20 ng/mL), 42.3% were insufficient (20 ng/mL < 25(OH) vitamin D < 30 ng/mL), only 16.9% were sufficient (25(OH) vitamin D > 30 ng/mL). Compared with the control group, children undergoing adenotonsillectomies exhibited a significant decrease in the level of serum 25(OH) vitamin D and %Tregs (p < 0.01, p < 0.01). The level of 25(OH) vitamin D and % Tregs did not correlate to parameters like BMI, age, sex in the children undergoing T&As. The lower Vitamin D levels were related to higher OSA-18 scores (Pearson correlation, r = -0.476, p < 0.01), tonsil size (Spearman rank correlation, r = -0.563)and adenoid size (Spearman rank correlation, r = -0.291). In the different vitamin D concentration groups, the mean values of %Tregs were not equal (ANOVA, F = 7.389, p = 0.001).

Conclusion: Children undergoing T&As have a lower level of 25(OH) vitamin D and %Tregs. Low 25(OH) vitamin D levels were related to higher OSA-18 scores and greater lymphoid tissue size rather than sex, age, increased BMI. Vitamin D and Treg cells are associated with adenotonsillar hypertrophy.