Introduction:
Urticaria is a common disease in the pediatric population. It is characterized by the presence of wheals, angioedema or coexistence of these changes. The pathomechanism of urticaria is associated with activation of the immune system, development of inflammation and changes in the coagulation system. The aim of the study was to analyze selected blood count parameters and their derivatives (neutrophil/lymphocyte ratio – NLR, platelet/lymphocyte ratio – PLR, mean platelet volume/platelet count ratio – MPR), C-reactive protein (CRP) and D-dimers in children with acute urticaria (AU) and chronic urticaria (CU) to assess their suitability for predicting the occurrence and activity of the disease.

Material and methods:
We performed a retrospective analysis of the clinical data and selected laboratory results in 125 children with urticaria (76 with AU and 49 with CU) hospitalized in our center between 2013 and 2019. The control group consisted of 75 healthy children.

Results:
Based on logistic regression analysis, we recorded an increased risk of AU and CU occurrence in the case of elevated NLR, neutrophil count, white blood cells (WBC), CRP and D-dimer values. Statistical analysis revealed that the best predictor of urticaria development was an increase in D-dimers (area under the curve –AUC = 0.84, sensitivity 86%, specificity 69%, cut-off 390.0). In patients with AU the disease activity was positively correlated with CRP (r = 0.24, p = 0.04) and D-dimer levels (r = 0.28, p = 0.02). In CU there was a positive correlation between disease activity and NLR (r = 0.44, p < 0.001), WBC (r = 0.30, p = 0.04) and CRP values (r = 0.35, p = 0.01).

Conclusions:
Increased CRP, WBC, NLR, platelet and D-dimer levels reflect the activation of inflammation and fibrynolysis present in urticaria. Further studies are required to determine the utility of these parameters as biomarkers of urticaria activity in children.