Alterations of coagulofibrinolytic-related markers in children with severe Mycoplasma pneumoniae pneumonia

Objective Severe Mycoplasma pneumoniae pneumonia (SMPP) in children can cause multiple systemic complications. This study aimed to explore changes in coagulofibrinolytic biomarkers and their predictive value for SMPP. Methods A total of 133 hospitalized children with Mycoplasma pneumoniae pneumonia (MPP) were retrospectively enrolled from March 2025 to April 2026. Patients were divided into the general MPP (GMPP, n = 63) and severe MPP (SMPP, n = 70) groups according to Guideline for management of community-acquired pneumonia in children (2024 version). Demographic, clinical features, inflammatory and coagulofibrinolytic laboratory data were extracted from electronic medical records. erformance of candidate biomarkers. Results Compared with the GMPP group, children with SMPP exhibited significantly higher neutrophil-to-lymphocyte ratio (NLR), C-reactive protein (CRP), fibrinogen (FIB), D-dimer, fibrin degradation products (FDP), tissue plasminogen activator-inhibitor complex (t-PAIC), thrombin-antithrombin complex (TAT), and plasmin-α2-plasmin inhibitor complex (PIC) ( P < 0.05). Multivariate logistic regression demonstrated that elevated PIC (OR = 1.004, 95%CI:1.002–1.005, P < 0.001) and NLR (OR = 1.514, 95%CI:1.037–2.210, P = 0.032) were independent risk factors for SMPP. The threshold value of PIC for predicting SMPP was 1185.5 ng/mL (AUC = 0.838, sensitivity 81.4%, specificity 77.8%). The combined model of PIC and NLR achieved an AUC of 0.876 with improved specificity (84.1%). D-dimer levels were markedly higher in patients with endobronchial mucus plugs than those without mucus plugs ( P = 0.035). Conclusions Activation of the coagulation-fibrinolysis system is prominent in children with SMPP. PIC and NLR serve as risk factors for severe MPP. The combination of PIC and NLR shows good predictive efficacy for SMPP in pediatric patients.