Serum free light chain (FLC) concentration is greatly affected by kidney function. Using a large prospective population-based cohort, we aimed to establish a reference interval for FLCs in persons with chronic kidney disease (CKD). A total of 75422 participants of the iStopMM study were screened with serum FLC, serum protein electrophoresis and immunofixation. Estimated glomerular filtration rate (eGFR) was calculated from serum creatinine. Central 99% reference intervals were determined, and 95% confidence intervals calculated. Included were 6461 (12%) participants with measured FLCs, eGFR < 60 mL/min/1.73 m2, not receiving renal replacement therapy, and without evidence of monoclonality. Using current reference intervals, 60% and 21% had kappa and lambda FLC values outside the normal range. The FLC ratio was outside standard reference interval (0.26–1.65) in 9% of participants and outside current kidney reference interval (0.37–3.10) in 0.7%. New reference intervals for FLC and FLC ratio were established. New reference intervals for the FLC ratio were 0.46–2.62, 0.48–3.38, and 0.54–3.30 for eGFR 45–59, 30–44, and < 30 mL/min/1.73 m2 groups, respectively. The crude prevalence of LC-MGUS in CKD patients was 0.5%. We conclude that current reference intervals for FLC and FLC ratio are inaccurate in CKD patients and propose new eGFR based reference intervals to be implemented.
血清游离轻链浓度受肾功能影响显著。本研究基于大型前瞻性人群队列，旨在为慢性肾病患者建立游离轻链参考区间。iStopMM研究共纳入75422名参与者，接受血清游离轻链检测、血清蛋白电泳及免疫固定电泳分析。通过血清肌酐计算估算肾小球滤过率。确定中心99%参考区间并计算95%置信区间。最终纳入6461名（12%）参与者，其游离轻链检测值可测、估算肾小球滤过率＜60 mL/min/1.73 m²、未接受肾脏替代治疗且无单克隆性证据。使用现行参考区间时，60%和21%参与者的κ和λ游离轻链值超出正常范围。9%参与者的游离轻链比值超出标准参考区间（0.26-1.65），0.7%超出当前肾脏参考区间（0.37-3.10）。研究建立了游离轻链及其比值的新参考区间：估算肾小球滤过率45-59、30-44及＜30 mL/min/1.73 m²组对应的游离轻链比值新参考区间分别为0.46-2.62、0.48-3.38和0.54-3.30。慢性肾病患者中轻链型意义未明单克隆丙种球蛋白病的粗患病率为0.5%。结论认为现行游离轻链及其比值参考区间对慢性肾病患者不准确，建议实施基于估算肾小球滤过率的新参考区间。
肿瘤(癌症)患者之家