Objective To explore serum levels of serine/threonine protein kinase 4(MST4)and heat shock protein 70(HSP70)in children with idiopathic immune thrombocytopenia(ITP)and their clinical signifi-cance.Methods Totally 98 children with ITP admitted to Northwest Women and Children's Hospital from April 2019 to April 2023 were retrospectively selected as the ITP group,and 50 healthy children who under-went physical examination during the same period were selected as the control group.Enzyme linked immu-nosorbent assay was used to detect serum levels of MST4 and HSP70,and the serum MST4 and HSP70 levels in children with different ITP levels were compared.The correlation between the indicators were analyzed by Pearson correlation.Logistic regression model was used to screen the prognostic factors of ITP,and the as-sessment value of serum MST4 and HSP70 on ITP prognosis was analyzed by subject working characteristic curve.Results Serum MST4,HSP70,and CD8 in the ITP group were higher than those in the control group,while PLT,CD3+,CD4+,CD4+/CD8+were lower than those in the control group,with statistical significance(P＜0.05).Serum MST4 and HSP70 levels in mild group,moderate group and severe group were increased successively,with statistical significance(P＜0.05).Correlation analysis showed that serum MST4 and HSP70 were positively correlated with CD8+(P＜0.05),and negatively correlated with PLT,CD3+,CD4+,CD4+/CD8+(P＜0.05).The disease course,serum MST4 and HSP70 of ITP children in the poor prognosis group were higher than those in the good prognosis group,and the differences were statistically significant(P＜0.05).Logistic regression analysis showed that the course of disease(OR=1.579,P＜0.001),serum MST4(OR=1.451,P＜0.001)and serum HSP70(OR=1.442,P＜0.001)were independent risk factors af-fecting the prognosis of children with ITP.The area under the curve of serum MST4 and HSP70 combined in the assessment of poor prognosis of ITP children was larger than that of serum MST4 and HSP70,and the difference was statistically significant(Z=4.568,4.672,both P＜0.001).Conclusion The elevated serum MST4 and HSP70 levels in children with ITP are related to the severity of the disease and cellular immune function.The combination of the two has a high evaluation value for the prognosis of children with ITP.