Abstract:Objective To study the value of combined measurements of WBC, lactate dehydrogenase (LDH), Creactive protein (CRP), erythrocyte sedimentation rate (ESR) and procalcitonin (PCT) in the etiological diagnosis of long-range fever in children. Methods By querying the case management system in Xiangya Hospital, 291 cases with definite diagnosis were the objects of our study. They were sorted by infection ( n= 202), rheumatism (n = 74) and tumor ( n= 15). The quantitative values of serum WBC, LDH, CRP, ESR and PCT were collected and their average values of the groups were compared. The diagnosis value of each parameter or the five parameters together were analyzed using the receiver operating characteristic (ROC) curve. Results The average levels of serum WBC,LDH, CRP, ESR and PCT were all elevated in each group. LDH elevated most in the tumor group, so did PCT in the rheumatism group. When compared with the infection group, serum levels of CRP, ESR and PCT were higher in the rheumatism group and serum levels of CRP, ESR and LDH were higher in the tumor group. According to the area under the ROC curve (AUC), CRP (0.672) and ESR (0.697) had much higher diagnostic value in identification of infection, CRP (0.739), ESR (0.739) and PCT (0.835) served better in diagnosis of rheumatism, so did PCT (0.827)and CRP (0.711) for tumor diagnosis. CRP and ESR had the highest AUC and Youden's index in the rheumatism group. PCT showed comparatively higher AUC, sensitivity, specificity and Youden's index in the rheumatism group and the tumor group. The five parameters together had greater significance in diagnosis of long-range fever in children since they had larger AUC in both infection group and tumor group. When considering the rheumatism group, the AUC of combined measurement was larger than that of single parameter except PCT. Conclusons Serum levels of CRP, ESR and PCT are valuable in diagnosis of rheumatism and tumor in children with fever longer than 14 days. WBC and LDH only have limited significance in differentiation of etiologies of long-range fever in children.Compared with single parameter, combined measurements have showen higher efficiency in clinical diagnosis.