Interleukin (IL)-1b, interleukin 18, and absolute lymphocytic count as biomarkers to differentiate primary immune thrombocytopenia from secondary immune thrombocytopenia

Background Primary immune thrombocytopenia (ITP) is an autoimmune disorder characterized by a platelet count below 100 × 10 3 /µl without other causes. This cytokines family play a key role in inflammation and immune regulation, helping to differentiate ITP from other types of thrombocytopenia and aiding in its diagnosis. This study aimed to evaluate the role of Interleukin (IL)-1b, IL-18, and absolute lymphocytic count (ALC) as biomarkers to differentiate primary ITP from secondary ITP. Patients and methods This case-control study was done on 150 patients, aged greater than 18 years, both sexes, with ITP and platelet count less than 100000/ul. Patients were divided into three equal groups: group A: with primary ITP, group B: with secondary ITP, and group C: age-sex matched healthy individuals. Results IL-18 and IL-1b were significantly higher in secondary ITP compared with primary ITP and control ( P <0.05) and was significantly lower in primary ITP compared with control ( P <0.05). ALC was higher in primary ITP than in secondary ITP and control ( P <0.001). There was a significant positive correlation between IL-1b [erythrocyte sedimentation rate (r=0.255, P =0.001) and IL-18 (r=0.504, P <0.001)]. IL-18 can significantly predict secondary ITP at [area under the curve (AUC) 0.896], 84% sensitivity, 89% specificity, 79.2% positive predictive value, and 91.8% negative predictive value. IL-1b can significantly predict primary ITP at (AUC 0.845), 82% sensitivity, 81% specificity, 68.3% positive predictive value, and 90.0% negative predictive value. Conclusion Secondary ITP had more levels of IL-18, IL-1b in comparison with primary ITP, while ALC is higher in primary ITP compared with secondary ITP and control.