目的 分析348例儿童传染性单核细胞增多症（IM）患儿临床特征及实验室检查结果。方法 回顾性分析2019年1月-2022年2月住院IM患儿的临床特征、并发症及实验室检查结果。结果 共纳入348例IM患儿，男185例、女163例，年龄1~15岁，以4~6岁为主（49.1%）；发病季节以夏季为主，6~8月份为高发期。主要临床表现为发热289例（83.0%）、眼睛浮肿192例（55.2%）、鼻塞182例（52.3%）。与≤3岁和4~6岁组相比，>6岁组发热比例较低，咽峡炎比例较高；>6岁组颈淋巴结肿大比例高于≤3岁组；4~6岁组肝脾肿大比例高于≤3岁组；≤3岁组鼻塞比例高于4~6岁组，差异均有统计学意义（P<0.05）。≤3岁、4~6岁、>6岁组之间淋巴细胞计数、CD4⁺/CD3⁺、CD8⁺/CD3⁺、CD4⁺/CD8⁺、谷氨酸氨基转移酶、谷氨酰转肽酶、乳酸脱氢酶差异有统计学意义（P<0.05）。IM患儿并发症以肝损伤133例（38.2%）为主，其次为中性粒细胞减少症（53例，15.22%）、脓毒症（27例，7.75%）。与非肝损伤组相比，肝损伤组男性比例较低，年龄较大，淋巴细胞计数较高，中性粒细胞-淋巴细胞比值（NLR）和单核细胞-淋巴细胞比值（MLR）较低，差异有统计学意义（P<0.05）。结论 儿童IM发生率高，以学龄前期儿童为主，早期临床表现多变不典型，肝损伤为最常见并发症。性别、年龄、淋巴细胞计数、NLR和MLR可能与肝损伤相关。

Objective To analyze the clinical characteristics and laboratory findings of 348 children with infectious mononucleosis (IM). Methods Clinical features, complications and laboratory findings of children hospitalized with IM from January 2019 to February 2022 were included. The clinical characteristics, complications and laboratory indicators were retrospectively analyzed. Results A total of 348 children with IM were included, 185 male (53.2 %) and 163 female (46.8 %), aged 1-15 years old, mainly 4-6 years old (preschool group) (49.1 %) ; The season of onset was mainly in summer, with a high incidence in June-August. The main clinical symptoms were fever in 289 cases (83.0 %), eyelid edema in 192 cases (55.2 %), nasal obstruction 182 cases (52.3 %). Compared with the ≤3 years old and 4-6 years old groups, the >6 years old group had a lower proportion of fever and a higher proportion of pharyngitis (P<0.05). The incidence of angina and lymphadenopathy in school-age group was significantly higher than ≤3 years old group (infant group) (P<0.05), and the incidence of hepatosplenomegaly in preschool group was significantly higher than the other two groups (P<0.05). The symptom of nasal obstruction in infant group was significantly higher than other two groups (P<0.05). The differences in lymphocyte counts, CD4⁺/CD3⁺, CD8⁺/CD3⁺, CD4⁺/CD8⁺, glutamate aminotransferase, glutamyl transpeptidase, and lactate dehydrogenase between the ≤3, 4-6, and >6 year old groups were statistically significant (P<0.05). Complications in children with IM were predominantly liver injury in 133 cases (38.2 %), followed by neutropenia (53 cases, 15.22 %), and sepsis (27 cases, 7.75 %). Compared to the non-hepatic injury group, the hepatic injury group had a lower proportion of males, older age, higher lymphocyte counts, and lower neutrophil-lymphocyte ratios (NLR) and monocyte-lymphocyte ratios (MLR), with a statistically significant difference (P<0.05). Conclusion IM in children has a high incidence, predominantly in preschool children, with variable and atypical early clinical manifestations and liver injury as the most common complication. Gender, age, lymphocyte count, NLR and MLR may be associated with liver injury.