Abstract: Objective To explore the levels of serum granulocyte colony-stimulating factor (G-CSF), lactate dehydrogenase 3 (LDH3), and cysteinyl leukotrienes (CysLTs) in children with severe Mycoplasma pneumoniae pneumonia, and to analyze their value in predicting clinical outcomes. Method From July 2022 to July 2024, 98 children with severe Mycoplasma pneumoniae pneumonia admitted to our hospital were regarded as the study subjects (severe group), simultaneously, 114 children with mild Mycoplasma pneumoniae pneumonia admitted to our hospital were included as the mild group, and 100 healthy children who underwent physical check-ups were selected as the control group. The general information, serum levels of G-CSF, LDH3, CysLTs, as well as indicators of forced expiratory volume in 1 second (FEV₁), forced vital capacity (FVC) were analyzed and compared among the three groups. Pearson correlation analysis was used to assess the correlation between serum G-CSF, LDH3, CysLTs and lung function indicators in children with severe Mycoplasma pneumoniae pneumonia. Based on the treatment effect, children with severe Mycoplasma pneumoniae pneumonia were assigned into the effective treatment group (n=67) and the ineffective treatment group (n=31). Logistic regression analysis was applied to analyze the factors affecting the outcome of children with severe Mycoplasma pneumoniae pneumonia. The receiver operating characteristic (ROC) curve was applied to analyze the predictive value of serum G-CSF, LDH3, and CysLTs ffor treatment efficacy in children with severe Mycoplasma pneumoniae pneumonia. Results The lymphocyte count, FEV₁, and FEV₁/FVC levels in the severe group were obviously lower than those in the mild group and the control group (P<0.05). The levels of serum G-CSF, LDH3, and CysLTs in the severe group were obviously higher than those in the control group and mild group (P<0.05). In children with severe Mycoplasma pneumoniae pneumonia, serum G-CSF, LDH3, and CysLTs were positively correlated with each other (P<0.05), and all three were negatively correlated with FEV₁ and FEV₁/FVC (P<0.05). The lymphocyte count, FEV₁, and FEV₁/FVC in the effective treatment group were obviously higher than those in the ineffective treatment group (P<0.05), while the levels of serum G-CSF, LDH3, and CysLTs were obviously lower than those in the ineffective treatment group (P<0.05). Higher levels of G-CSF, LDH3, and CysLTs were risk factors for ineffective treatment in children (P<0.05), while FEV₁/FVC was a protective factor (P<0.05). The AUC of the combination of G-CSF, LDH3, and CysLTs for predicting treatment efficacy was 0.869, which was better than single indicator detection (Z_{G-CSF-combination}=2.791, P=0.005, Z_{LDH3- combination}=2.087, P=0.037, Z_{CysLTs-combination}=2.963, P=0.003). Conclusion The serum levels of G-CSF, LDH3, and CysLTs in children with severe Mycoplasma pneumoniae pneumonia are elevated, and they are related to the disease outcome. Combined measurement of the three may have value in predicting the clinical outcome of children with severe Mycoplasma pneumoniae pneumonia.

Key words: Severe Mycoplasma pneumoniae pneumonia, Granulocyte colony-stimulating factor, Lactate dehydrogenase 3, Cysteinyl leukotrienes, Outcome, Predictive value, Children