Abstract:Objective To analyze the levels of serum amyloid A (SAA), serum procalcitonin (PCT) and white blood cell (WBC) in children with hand-foot-and-mouth disease (HFMD) caused by enterovirus 71. To compare the correlation between the above indexes and creatine kinase (CK), creatine kinase MB isoenzyme (CKMB) and lactate dehydrogenase (LDH). To explore the diagnostic value of SAA, PCT and WBC in children with HFMD caused by enterovirus 71. Methods Sixty children with HFMD caused by enterovirus 71 in our hospital from October 2018 to October 2019 were selected. The demographic data and clinical characteristics and manifestations of the infection were analyzed. According to the clinical symptoms, the patients were divided into severe group and mild group, and 30 healthy children were selected as the control group. The average levels of SAA, PCT and WBC in each group were compared, and the changes of CK, CKMB and LDH in each group were detected. The correlation between the two sets of indicators was analyzed. Results The HFMD children with mild enterovirus 71 infection were mainly characterized by fever and rash, in which the fever lasted for more than 72 hours (56.66%), and the rash was mainly distributed in the hand, foot, mouth or hip (86.68%). HFMD children with severe enterovirus 71 infection had a variety of neurological and respiratory symptoms and cardio-pulmonary and cerebral complications. The main neurological symptoms were lethargy (83.33%), nausea and vomiting (70.00%) and clonic convulsions (60.00%). Respiratory symptoms were characterized by increased respiratory rate (53.33%), and complications were mainly myocardial injury (33.33%). There were significant differences in SAA (F =88.849, P < 0.05), PCT (F =94.396, P < 0.05) and WBC (F =24.943, P < 0.05) among the three groups. The values of SAA, PCT and WBC in children with HFMD were significantly higher than those in healthy children in control group (P < 0. 05). Besides, SAA and PCT in children with severe enterovirus 71 infection were also significantly higher than those in children with mild infection (P < 0. 05). The area under ROC curve of SAA, PCT, and WBC was respectively 0.993 (95% CI: 0.976, 1.000), 0.995 (95% CI: 0.982, 1.000) and 0.939 (95% CI: 0.868, 1.000) in the severe group compared with control group, while that was 0.913 (95% CI: 0.796, 1.000), 0.911 (95% CI: 0.793, 1.000) and 0.756 (95% CI: 0.607, 0.906) separately in the severe group compared with mild group. There were significant differences in CK (F =2974.874, P < 0.05), CKMB (F =20.057, P < 0.05) and LDH (F =77.231, P < 0.05) among the three groups. The values of CK, CKMB and LDH in HFMD children with severe enterovirus 71 infection were significantly higher than those in children with mild infection and healthy children (P < 0. 05). There was a significant positive correlation between CK and SAA (rs =0.565, P < 0.001), PCT (rs =0.795, P < 0.001), WBC (rs =0.401, P = 0.010), CKMB and SAA (rs =0.416, P = 0.008), PCT (rs =0.359, P = 0.023) and WBC (rs =0.315, P = 0.048), as well as LDH and SAA (rs =0.550, P < 0.001), PCT (rs =0.358, P = 0.023) and WBC (rs =0.354, P = 0.025). Conclusions SAA, PCT and WBC are of certain value in the diagnosis of HFMD caused by enterovirus 71, and the detection together with the CK, CKMB and LDH plays an essential role in predicting the condition of HFMD changing from mild to severe.