Abstract: Objective To evaluate the clinical relevance of the monocyte/lymphocyte ratio (MLR), the CD4⁺T cell/CD8⁺ T cell ratio (CD4⁺/CD8⁺) and the aspartic aminotransferase/platelet ratio index (APRI) in pediatric patients with infectious mononucleosis (IM) complicated by hepatic injury. Methods From January 2021 to October 2022, a cohort of 200 pediatric patients with IM was enrolled from the Department of Pediatrics at Hai 'an People's Hospital. These patients were assigned into liver damage (n=157) and non-liver damage groups (n=43) based on the presence of abnormal liver function. Further subdivision of the liver damage group was based on liver function test results into mild(n=77), moderate (n=59), and severe(n=21) liver damage subgroups . Additionally, children tested for EB virus DNA (EBV DNA) were classified according to viral load into low(n=32), medium(n=97), and high(n=28) load groups. Post-treatment, patients were divided based on EBV DNA load into negative(n=116) and non-negative (n=41) groups after one week.. We collected and compared general demograoghics, hematological parameters, liver function, and serological markers across these groups. Pearson correlation analyzsis was employed to evaluate the relationships between MLR, CD4⁺/CD8⁺ ratios, APRI, and hypersensitive C-reactive protein (hs-CRP), adenosine deaminase (ADA) and the duration of liver damage. Receiver operating characteristic (ROC) curves were utilized to assess the diagnostic effectiveness of combined and individual biomarker. Results Neutrophil (NEU) and platelet (PLT) count levels were significantly lower in the liver damage group compared to the non-liver damage group. Conversely, age, monocyte (MO), lymphocyte ratio (LYM), alanine aminotransferase (ALT), aspartate aminotransferase (AST), adenosine deaminase (ADA), hs-CRP and EBV DNA load were significantly higher in the liver damage group(P<0.05). No significant differences were found in sex, body mass index (BMI), disease duration, albumin (Alb), total bilirubin (TBil) and direct bilirubin (DBil) between the groups (P>0.05). Within the liver damage category, MLR and CD4⁺/CD8⁺ ratios in the severe subgroup( 0.15±0.04 and 0.88±0.32, respectively) were, lower than those in the moderate(0.18±0.05 and 1.09±0.37) and mild subgroups(0.25±0.07, 1.22±0.41). The APRI was also higher in the severe subgroup( 1.24±0.25) compared to mderate(1.13±0.20) and mild subgroups(1.05±0.17), with all differences being statistically significant (F=13.584, 14.267, 11.459, all P<0.05). In high-load EBV DNA groups, MLR and CD4⁺/CD8⁺ ratios were lower than in medium and low-load groups, with statistically significant difference in APRI values as well(P<0.05). Similarly, in the non-negative post-treatment subgroup, MLR and CD4⁺/CD8⁺ ratios were lower than in the negative subgroup, and APRI was significantly higer in the non-negative subgroup (P<0.05). Pearson correlation analysis demonstrated that MLR, CD4⁺/CD8⁺ ratios negatively correlated with hs-CRP, ADA and the duration of liver damage in children with IM, whereas APRI showed a positively correlation (P<0.01). ROC analysis revealed that the combined diagnostic test for MLR, CD4⁺/CD8⁺ and APRI had higher sensitivity and specificity than any single test(P<0.05), with AUC values of 0.539, 0.905, 0.854, and 0.978 respectively. Conclusion MLR, CD4⁺/CD8⁺ and APRI represent straightforward and dependable serological markers. Their collective assessment offers significant value for evaluating disease severity and prognosis in children with IM complicated by liver damage.

Key words: IM, Liver damage, MLR, CD4⁺/CD8⁺, APRI, Assessed value