Objective To investigate the expression of serum soluble myeloid cell trigger receptor 1(sTREM-1), interleukin-21(IL-21), 25 (OH) vitamin D25(OH)Din children with inflammatory bowel disease and their relations.

Methods A total of 107 children with inflammatory bowel disease were selected as research objects and included in observation group. At the same time, 53 healthy people were selected as control group. The patients in the observation group were divided into active stage group (n=54) and remission stage group (n=53) according to disease activity. The expression of sTREM-1, IL-21, 25(OH)D were compared between the observation group and the control group and between active stage group and remission stage group. Kendall's tau-b method was used to analyze the correlations of sTREM-1, IL-21 and 25(OH)D with inflammatory bowel disease activity. Receiver operating characteristic (ROC) curve model was used to analyze the area under the curve (AUC) value, sensitivity and specificity of sTREM-1, IL-21 and 25(OH)D in the diagnosis and prediction of inflammatory bowel disease (IBD).

Results The serum levels of sTREM-1 and IL-21 in the observation group were higher than those in the control group, but level was lower than that in the control group (P < 0.05). The serum levels of sTREM-1 and IL-21 levels in the active stage group were higher than those in the remission stage group, but 25(OH)D level was lower than that in the remission stage group (P < 0.05). Kendall′s tau-b correlation analysis showed that sTREM-1 and IL-21 were positively correlated with inflammatory bowel disease activity (r=0.460, 0.484; P < 0.05). 25(OH)D was negatively correlated with inflammatory bowel disease activity (r=-0.434, P < 0.05). ROC curve analysis showed that the AUC values of sTREM-1, IL-21, 25(OH)Dand their combination in the diagnosis of inflammatory bowel disease were 0.791, 0.852, 0.808, 0.862, respectively(P < 0.05), and the sensitivities were 74.80%, 81.30%, 75.50% and 81.30%, respectively. The specificities were 75.50%, 75.50%, 81.30% and 79.20%, respectively. The AUC values of sTREM-1, IL-21, 25(OH)D and their combination in predicting the active phase of inflammatory bowel disease were 0.821, 0.840, 0.799, 0.840, respectively (P < 0.05), the sensitivities were 79.60%, 75.90%, 77.40% and 87.00%, respectively, and the specificities were 79.20%, 75.50%, 83.30% and 79.20%, respectively.

Conclusion Serum levels of sTREM-1, IL-21, 25(OH)D are closely related to the occurrence and development of inflammatory bowel disease. Dynamic monitoring of their levels is helpful to provide an important reference for clinical diagnosis of inflammatory bowel disease and evaluation of disease progression in children.