目的：探讨新型尿游离轻链（urine free light chain，uFLC）检测在尿轻链定量监测方面是否优于传统尿总轻链（urine total light chain，uTLC）检测。方法：收集2022年1月至2023年3月间上海交通大学医学院附属瑞金医院的280例患者（包括浆细胞疾病患者153例和非浆细胞疾病患者137例）的血、尿配对样本，共458例次。应用卡方检验、McNemar配对检验和Spearman相关性分析等方法，统计检测的uFLC和uTLCκ值、λ值、κ/λ比值结果，并分析其与尿免疫固定电泳（urine immunofixation electrophoresis, uIFE）、血游离轻链（serum free light chain，sFLC）等检测结果之间的阳性相符率及相关性。结果：102例次uIFE阳性的样本中，88.2%（90/102）的样本有uFLC κ/λ比值异常，87.3%（89/102）的样本有uTLC κ/λ比值异常（P<0.001）。在183例次sFLC κ/λ比值异常的样本中，65.6%（120/183）的样本存在uFLC κ/λ比值异常，51.4%（94/183）的样本存在uTLC κ/λ比值异常（P<0.001）。457例次同时检测了uFLC和uTLC的样本中，164例次（35.9%）的uFLC κ/λ比值异常，123例次（26.9%）的uTLC κ/λ比值异常（P<0.001）。uFLC检测与uTLC检测的相应κ值、λ值、κ/λ比值之间均有着较强的相关性（r值分别为0.849、0.697和0.648，P<0.001）；uFLC检测与sFLC检测的相应κ值、λ值、κ/λ比值之间的相关系数r值分别为0.628、0.552和0.640（P<0.001）；而uTLC与sFLC检测的κ值、λ值、κ/λ比值之间的相关系数r值分别为0.520、0.533和0.551（P<0.001），均为中等相关。与uTLC与sFLC结果之间的相关性相比，uFLC与sFLC结果间的相关性更强。结论：uFLC检测在尿轻链定量监测方面较uTLC检测更灵敏，其结果与uIFE及sFLC等检测结果间的阳性相符率及相关性更高，能更客观地反映尿轻链的定量，在临床尿轻链定量监测中，可优先行uFLC检测。

Objective: To explore whether the novel urine free light chain (uFLC) assay is superior to the traditional urine total light chain (uTLC) assay in quantitative monitoring of urine light chain. Methods: A total of 458 paired samples of blood and were collected from 280 patients (including 153 patients with plasma cell diseases and 137 patients with non-plasma cell diseases) from January 2022 to March 2023 at Ruijin Hospital， Shanghai Jiao Tong University School of Medicine. The positive concordance rates and correlations between the κ value, λ value and κ/λ ratio of uFLC and uTLC assays with the results of urinary immunofixation electrophoresis (uIFE) and serum free light chain (sFLC) were analyzed by Chi-squared test, MeNemar’s test and Spearman correlation coefficient calculation. Result: Among the 102 uIFE positive samples, 88.2% (90/102) of the samples had abnormal uFLC κ/λ ratio, and 87.3% (89/102) had abnormal uTLC κ/λ ratio (P<0.001). Among the 183 samples with abnormal sFLC κ/λ ratio, 65.6% (120/183) of the samples had abnormal uFLC κ/λ ratio, and 51.4% (94/183) had abnormal uTLC κ/λ ratio (P<0.001). Among the 457 samples with both uFLC and uTLC results, 164 samples (35.9%) had abnormal uFLC κ/λ ratio, and 123 samples (26.9%) had abnormal uTLC κ/λ ratio (P<0.001). There was a strong correlation between the levels of κ light chain, λ light chain, and κ/λ ratio of uFLC and uTLC (r values were 0.849, 0.697 and 0.648, respectively, P<0.001). The r values between the levels of corresponding κ light chain, λ light chain, and κ/λ ratio of uFLC and sFLC were 0.628, 0.552, and 0.640 (P<0.001), while the r values between the levels of κ light chain, λ light chain, and κ/λ ratio of uTLC assay and sFLC assay were 0.520, 0.533, and 0.551, respectively (P<0.001). Moderate correlations were indicated and the correlation between uFLC and sFLC was stronger than that between uTLC and sFLC. Conclusions: Compared with the uTLC assay, the uFLC assay is more sensitive in the quantitative monitoring of urine light chain and has higher positive concordance rates and stronger correlations with uIFE and sFLC results, indicating an objective quantitative determination of urine light chain. It is recommended to prioritize the use of uFLC assay in clinical quantitative monitoring of urinary light chain.