Objective:To explore the value of serum copeptin, S100B protein and uric acid (UA) levels in the prognosis of children with traumatic brain injury (TBI).Methods:Eighty-six children with TBI admitted to Danzhou People's Hospital from January 1st, 2017 to December 31st, 2019 were selected. The gender, age, body mass index (BMI), cause of TBI, and baseline data of body temperature, heart rate (HR) and respiratory rate (RR) were collected, and the serum copeptin, S100B protein and UA levels were recorded on the 1st, 3rd and 5th day after admission. According to 28-day prognosis, the children were divided into survival group and death group. According to the Glasgow coma score (GCS) at admission, the children were divided into moderate group (GCS score 9-12) and severe group (GCS score 3-8). The changes of serum copeptin, S100B protein and UA level of each group were observed on the 1st, 3rd and 5th day after admission. Receiver operator characteristic (ROC) curve was drawn to analyze the value of serum copeptin, S100B protein and UA in predicting the death of TBI children in 28 days. Pearson correlation method was used to analyze the correlation between GCS score and serum copeptin, S100B protein and UA in dead children during 28 days.Results:Eighty-six children were enrolled in the final analysis, 35 died and 51 survived in 28 days, with 28 in moderate coma and 58 in severe coma. There was no significant difference in the baseline data between the different prognosis groups. The serum copeptin, S100B protein and UA levels of the children in the death group on the 1st day after admission were significantly higher than those in the survival group, and showed an increasing trend with the extension of hospitalization. The differences between the death group and the survival group on the 5th day were still statistically significant [copeptin (μg/L): 19.37±6.50 vs. 8.06±2.14, S100B protein (μg/L): 9.52±2.86 vs. 3.75±0.97, UA (μmol/L): 527.40±273.84 vs. 255.38±143.75, all P < 0.01]. The levels of serum copeptin, S100B protein and UA in the severe group also increased over time, and were significantly higher than those in the moderate group [5-day copeptin (μg/L): 17.84±4.73 vs. 9.15±2.42, 5-day S100B protein (μg/L): 8.80±2.40 vs. 4.17±1.16, 5-day UA (μmol/L): 494.72±262.53 vs. 276.20±150.37, all P < 0.01]. ROC curve analysis showed that serum copeptin, S100B protein and UA at each time point after admission had predictive value for 28-day death of TBI children, and the most predictive value was on the 3rd day, and the area under ROC curve (AUC) predicted by the combination of three parameters were significantly higher than that predicted by a single one (AUC: 0.940 vs. 0.852, 0.837, 0.793, Z values were 5.392, 5.704 and 6.612, respectively, all P < 0.05), with the sensitivity and specificity of 96.3% and 88.5%, respectively. Pearson correlation analysis showed that serum copeptin, S100B protein and UA were significantly negatively correlated with GCS score on the 3rd day after admission in 28-day dead TBI children ( r values were -0.862, -0.827, -0.758, respectively, all P < 0.01). Conclusions:The increase of serum copeptin, S100B protein and UA levels is related to the severity and prognosis of TBI children. The combination of serum copeptin, S100B protein and UA on the 3rd day after admission has a better value in predicting the death of TBI children.