Lujiang Yi^{1, 2}, Jia Wei³, Mengyao Yu^{1, 2}, Li Jiang^{1, 2}, Zhenzhen Cai^{1, 2,}

Objective: Recently, the incidence of MM (Multiple myeloma, MM) in the elderly has gradually increased. We explored the diagnosis efficiency of urine light chain ratio combined with immunofixation electrophoresis for preliminary screening elderly MM patients who had renal injury as the first symptom. Methods: A total of 981 elderly outpatients, newly diagnosed with renal injury, in our hospital from January 2017 to February 2019 were retrospectively reviewed. According to the results of immunofixation electrophoresis, they were divided into M-protein group and non-M-protein group. The laboratory test data of each group were collected. Results: Among the 981 enrolled cases, 84 cases were in the M-protein group, accounting for 8.6%. There was no statistically significant difference in Crea and eGFR between the M-protein group and the non-M-protein group. The KAP/LAM ratio was higher in the non-M group then that in the M-protein group with LAM type light chain expression, and was lower in the M-protein group with KAP type light chain expression (P<0.01). Compared with IgG, IgA and IgM groups, Crea and u-mALB/Crea were increased and eGFR was decreased in the simple light chain group (P<0.05). Significant differences in renal function indicators in kidney diseases caused by different causes in 897 non-M protein groups. However, there was no statistically significant difference between Kappa/Lambda ratios in blood and in urine. Conclusion: Urine light chain ratio had a higher specificity for initial screening of elderly MM patients with renal injury as the first symptom. It could reflect the degree of monoclonal proliferation. Moreover, it was easy to be accepted by patients and suitable for health checkup or preliminary screening of suspected MM patients.

multiple myeloma, urine light chain ratio, immunofixation electrophoresis, early preliminary screening