目的：评价尿路感染（urinary tract infection,UTI）报警信息辅助诊断临床UTI的应用价值。方法：用尿沉渣分析仪检测2 871例尿液标本,以临床诊断UTI为金标准,分析在默认设定值时仪器报警信息的诊断符合率、灵敏度和特异度。更改白细胞计数（white blood cell, WBC）和细菌计数（bacterial count, BACT）阈值,找到符合本院临床实际情况的最佳阈值,并验证其与临床诊断的符合情况。结果：以临床诊断UTI为金标准,仪器UTI报警信息的符合率为70.61%。在超过默认设定值（WBC>10个/μL和BACT>10个/μL）时,WBC的诊断灵敏度为94.23%,特异度为58.02%;BACT的诊断灵敏度为94.12%,特异度为68.98%;仪器UTI报警信息的诊断灵敏度为94.23%,诊断特异度为70.61%。由受试者操作特征曲线获得WBC和BACT 的最佳临界值分别为24.9个/μL和1 157.3个/μL,WBC和BACT诊断UTI的灵敏度取95%,特异度最高（WBC 56.8%,BACT 57.01%）时对应的值分别为26.7个/μL和60.1个/μL。经验证,当阈值设置为WBC 26.7个/μL和BACT 1 157.3个/μL时,仪器UTI报警信息的灵敏度、特异度最佳（灵敏度为93.34%,特异度为71.17%）。结论：调整阈值后,仪器的UTI报警信息有较高的诊断灵敏度和特异度,符合我院UTI早期诊断要求,可用于临床UTI的快速诊断。

Objective: To explore and optimize the settings of alarm in Sysmex UF5000 urinary tract infection (UTI) system to assist the diagnosis of UTI. Methods: A total of 2 871 urine samples were collected and tested by Sysmex UF5000 urine sediment analyzer. The diagnostic accurate rate, sensitivity, and specificity of the default alarm threshold settings of the instrument for UTI were calculated regarding to the clinical diagnosis of UTI. The thresholds of white blood cell count (WBC) and bacterial count (BACT) were optimized to meet the local hospital need. Results: The accurate rate of instrumental alarm settings for diagnosing UTI was 70.61%, with a sensitivity of 94.23% and specificity of 70.61%. At the default setting, the diagnostic sensitivities of WBC (WBC>10/μL) and BACT (BACT>10/μL) were 94.23% and 94.12%, while specificities were 58.02% and 68.98%. The optimal cutoff values for WBC and BACT determined by ROC curve were 24.9/μL and 1 157.3/μL, respectively. However, when sensitivities of WBC and BACT were set as 95%, the specificities of both parameters were 56.8% and 57.01%, yielding the cut-off values as 26.7/μL and 60.1/μL, respectively. Clinical validation showed that best sensitivity and specificity of the system was achieved(sensitivity 93.34%, specificity 71.17%) when the WBC and BACT were reset at 26.7/μL and 1 157.3/μL, respectively. Conclusion: Optimized the alarm threshold of the Sysmex UF5000 achieve higher sensitivity and specificity, assisting rapid diagnosis of clinical UTI.