The new serum free light chain (FLC) test, which is widely advocated internationally, was first carried out in China in October 2013, providing great clinical help! sFLC has the following advantages: 1. Abnormal serum free light chain κ/λ ratio can be used as an important criterion to determine benign and malignant plasma cell disease. Its determination is more sensitive than common M protein identification, serum protein electrophoresis and urine light chain, which can detect the treatment effect and disease relapse earlier; 2. During myeloma chemotherapy, patients with negative free light chain have longer survival than those with negative immunofixed electrophoresis (but positive free light chain), and can achieve deep remission sfLC (complete remission in strict sense); 4, especially for the diagnosis and treatment of IgD, light chain, non-secretory myeloma and amyloidosis, there is a unique and irreplaceable value; and it can be used as an indicator to determine the renal function of these patients; 5, currently it can also be used for the detection of lymphoma, CLL and other diseases! CLL and other diseases!