Objective: To investigate the diagnostic and prognostic values of serum free light chain (sFLC) in patients with primary light chain amyloidosis (pAL). Methods: Patients diagnosed with pAL between January 2009 and June 2015 at Peking Union Medical College Hospital were included in this study to retrospectively evaluate the clinical data, sFLC, treatment and survival. Results: In total, 126 newly diagnosed pAL patients with complete sFLC data were included in this study. The median age was 57 years old (range, 37-81 years) and male to female ratio was 1.57. Eighty patients (63.5%) had lambda type light chain. Renal and cardiac involvements occurred in 87 cases (69% ) and 79 cases (62.7% ), respectively. The median value of difference between involved and uninvolved serum immunoglobulin free light chain levels (dFLC) was 99 mg/L (range, 1-4 263 mg/L). The positive rate of serum protein electrophoresis, serum immune fixation electrophoresis, urine immunofixation electrophoresis and abnormal sFLC ratio to detect monoclonal immunoglobulin were 34.9%(44 cases), 63.5%(80 cases), 77.0%(97 cases) and 81.0% (102 cases), respectively. The sensitivity for identifying monoclonal immunoglobulin could be increased to 98.4%(124 cases) by using the above-mentioned four methods. The median follow-up was 16 months, 37 patients were dead at the last follow-up. The median overall survival of all patients were not reached. Multivariate analysis showed that dFLC≥130 mg/L was independently associated with inferior survival (HR=3.272, 95%CI 1.384-7.739, P=0.007). Conclusions: Serum FLC measurement combined with other methods could improve the sensitivity of detection of monoclonal immunoglobulin in patients with pAL. The high level of dFLC was an independent prognostic factor for survival.
目的: 研究血清游离轻链（sFLC）检测在原发性轻链型淀粉样变（pAL）中的诊断和预后价值。
方法: 回顾性分析2009年1月至2015年6月确诊且有完整sFLC数据的126例pAL患者的临床资料，探讨sFLC的诊断价值，并采用Cox回归法分析sFLC差值（dFLC）的预后价值。
结果: 126例患者中男女比例为1.57∶1，中位年龄为57 (37~81）岁，λ轻链型者80例（63.5%），肾脏受累者87例（69.0%），心脏受累者79例（62.7%）。126例患者的中位dFLC为99 (1~4 263）mg/L。血清蛋白电泳、血清免疫固定电泳、尿免疫固定电泳和sFLC比值异常法检测单克隆免疫球蛋白（M蛋白）的阳性检出率分别为34.9%（44/126）、63.5%（80/126）、77.0%（97/126）和81.0%（102/126）。联合上述四种方法可将M蛋白的检出率提高至98.4%（124/126）。中位随诊16个月后，37例患者死亡，所有患者的中位生存时间尚未达到。多因素分析发现dFLC ≥130 mg/L是影响pAL患者预后的独立危险因素（HR=3.272, 95% CI 1.384~7.739，P=0.007）。
结论: sFLC检测可显著提高pAL患者M蛋白的检出率；高水平dFLC是影响患者预后的独立危险因素。