Sprangers Ben, Claes Kathleen, Evenepoel Pieter, Kuypers Dirk, Poesen Koen, Delforge Michel, Bossuyt V Xavier, Meijers Björn
Department of Microbiology and Immunology, Laboratory of Molecular Immunology (Rega Institute), KU Leuven, Leuven, Belgium.
Division of Nephrology, University Hospitals Leuven, Leuven, Belgium.
Kidney Int Rep. 2020 Jan 30;5(5):627-631. doi: 10.1016/j.ekir.2020.01.019. eCollection 2020 May.
Quantification of serum-free light chains (FLCs) is important in the diagnosis and monitoring of paraprotein-related diseases. There are currently 2 FLC assays available: the Freelite assay (Binding Site) and the N Latex assay (Siemens). There is emerging evidence that these assays give different results, but it is not established how kidney dysfunction affects these assays differently.
In this study, we measured and compared serum FLCs in patients with mild-to-moderate chronic kidney disease (CKD) using both assays.
Although κ FLCs are higher by Freelite, λ FLCs are higher by N Latex. Both κ and λ FLCs correlate inversely with estimated glomerular filtration rate (eGFR) in the 2 assays, but this effect is more pronounced in λ-free light-chain measurement by N Latex. Consequently, although the κ/λ ratio by Freelite is inversely correlated by eGFR, the κ/λ ratio by N Latex is positively correlated with eGFR.
Our results clearly demonstrate that the 2 available FLC assays cannot be used interchangeably in patients with CKD.
血清游离轻链（FLC）的定量在副蛋白相关疾病的诊断和监测中具有重要意义。目前有两种FLC检测方法：Freelite检测法（Binding Site公司）和N Latex检测法（西门子公司）。越来越多的证据表明这些检测方法会给出不同的结果，但肾功能不全如何对这些检测方法产生不同影响尚未明确。
在本研究中，我们使用这两种检测方法对轻度至中度慢性肾脏病（CKD）患者的血清FLC进行了测量和比较。
虽然Freelite检测法测得的κ轻链较高，但N Latex检测法测得的λ轻链较高。在这两种检测方法中，κ和λ轻链均与估计肾小球滤过率（eGFR）呈负相关，但这种效应在N Latex检测法测量λ游离轻链时更为明显。因此，虽然Freelite检测法测得的κ/λ比值与eGFR呈负相关，但N Latex检测法测得的κ/λ比值与eGFR呈正相关。
我们的结果清楚地表明，现有的两种FLC检测方法在CKD患者中不能互换使用。
