Levinson Stanley S
Department of Pathology and Laboratory Medicine, University of Louisville, KY, USA.
Ann Clin Lab Sci. 2010 Fall;40(4):348-53.
There is controversy about whether a sensitive assay for the serum Ig free light chain (FLC) κ/λ ratio can replace urine immunofixation electrophoresis (UIFE). This report describes two untreated patients in whom monoclonal FLCs were identified in urine despite normal serum FLC κ/λ ratios. Unlike the classical serum electrophoretic patterns in multiple myeloma, both serum samples showed adequate amounts of polyclonal Ig. The most likely explanation is a masking effect by polyclonal FLC on the serum κ/λ ratio when sufficient concentrations of polyclonal FLC exist. These cases illustrate this likely effect and attest to the continued importance of UIFE for initial screening of patients for Bence-Jones protein.
血清游离轻链（FLC）κ/λ比值的敏感检测能否替代尿免疫固定电泳（UIFE）存在争议。本报告描述了两名未经治疗的患者，尽管血清FLC κ/λ比值正常，但尿液中仍检测到单克隆FLC。与多发性骨髓瘤的经典血清电泳图谱不同，两份血清样本均显示有多克隆Ig的充足含量。最可能的解释是，当存在足够浓度的多克隆FLC时，多克隆FLC对血清κ/λ比值产生了掩盖效应。这些病例说明了这种可能的效应，并证明了UIFE在初步筛查本-周蛋白患者方面的持续重要性。
