Abstract:

Background：Serum free light chain (FLC) assay has been confirmed to be a sensitive and critical assay in identifying monoclonal gammopathy.At present,the reference range is based on foreign literatures,lacking of large sample data in Chinese  patients.In renal dysfunction patients,serum FLC concentrations change,and the diagnostic performance of κ/λ ratio becomes controversial.
Ｏｂｊｅｃｔｉｖｅ：to measure the reference range of serum FLC in Chinese patients with chronic kidney disease (CKD) and its diagnostic value for monoclonal gammopathy.
Ｍｅｔｈｏｄｏｌｏｇｙ：A total of 2,711 patients who were hospitalized at the National Clinical Research of Kidney diseases in Jinling Hospital Affiliated to Nanjing University School of Medicine and tested for serum FLC were incorporated into observation and retrospectively analyzed.
Ｒｅｓｕｌｔｓ：Serum κFLC,λFLC and κ/λ were positively correlated with serum creatinine and cystatin C,and negatively correlated with eGFR.Reference ranges of κFLC(1075～6822 mg/L),λFLC(1216～5029 mg/L),and κ/λ(049～193) were set in patients with normal renal function and excluded for autoimmune disease or infection (95% confidence intervals) Extending to all renal function stages,the range of κFLC was 1110～15289 mg /L,λFLC was 1220～11853 mg/L,κ/λ was 052～236.A classification method based on renal function status has an optimal diagnostic performance.
Ｃｏｎｃｌｕｓｉｏｎ：As renal dysfunction worsens,serum FLC concentrations and κ/λ elevate,affecting their diagnostic performance  for monoclonal gammopathy.Patients with CKD should use different diagnostic ranges based on renal function status.

Key words: free light chain, monoclonal gammopathy, reference range, renal dysfunction