肾功能对慢性肾脏病血清游离轻链的影响

Renal function status influences serum free light chain concentrations in patients with chronic kidney disease

背景:血清游离轻链在单克隆免疫球蛋白病的诊断中有重要价值,目前其参考范围主要依据国外文献,缺乏中国大样本数据,随肾功能不全进展,κ/λ比值如何变化及其意义存在争议。目的:探索慢性肾脏病(CKD)患者血清游离轻链(FLC)的水平、参考范围及对单克隆免疫球蛋白病的诊断价值。方法:东部战区总医院国家肾脏病临床医学研究中心住院并检测血清游离轻链的患者共2 711例,对其临床资料进行回顾性分析。结果:血清κFLC、λFLC与血清肌酐、胱抑素C呈正相关,与估算的肾小球滤过率(eGFR)呈负相关;κ/λ存在相同的相关趋势,但与eGFR相关性较强(均P<0.01)。肾功能正常并除外单克隆免疫球蛋白病及自身免疫病、感染的CKD患者中(n=690),κFLC范围为10.75~68.22 mg/L,λFLC范围为12.16~50.29 mg/L,κ/λ范围为0.49~1.93(均为95%置信区间)。扩大至所有肾功能分期后,κFLC范围为11.10~152.89 mg/L,λFLC范围为12.20~118.53 mg/L,κ/λ范围为0.52~2.36。当按肾功能分层使用不同参考范围时,可提高诊断效率。结论:随肾功能不全进展,血清FLC水平及κ/λ比值升高,影响对单克隆球蛋白病的诊断效率,不同的肾功能状态CKD患者应选择不同的正常参考值范围。

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.