Immunoglobulin heavy light chain test quantifies clonal disease in patients with AL amyloidosis and normal serum free light chain ratio. (1st October 2016)

• Record Type: Journal Article
• Authors: Prokaeva, Tatiana; Spencer, Brian; Sun, Fangui; O'Hara, Richard M.; Seldin, David C.; Connors, Lawreen H.; Sanchorawala, Vaishali
• Is Part Of: Amyloid. Volume 23:Number 4(2016:Dec.)
• Page Start: 214
• Page End: 220
• Publication Date: 2016-10-01
• Subjects: AL amyloidosis -- Freelite® assay -- Hevylite® assay -- immunoglobulin heavy light chain; Amyloidosis -- Periodicals; 616.3995
• DOI: 10.1080/13506129.2016.1219715
• Languages: English
• ISSNs: 1350-6129

Abstract

Abstract: Background : Serum and urine immunofixation electrophoreses (SIFE/UIFE) are used for clonal detection in plasma cell dyscrasias, while serum free light chain (sFLC) testing provides quantitation of clonal disease. Up to 20% of patients with light chain (AL) amyloidosis may present with normal FLC ratio (FLCr). Methods : We assessed the diagnostic, quantitative and prognostic potential of serum heavy light chain ratio (HLCr) in 199 untreated patients at initial evaluation. Results : An abnormal HLCr was found in 37.2%, abnormal FLCr in 81.9% and positivity by SIFE/UIFE in 94% of patients. HLCr together with SIFE/UIFE identified clonality in 94% patients; the combination with FLCr yielded 100% sensitivity. An HLCr abnormality was significantly over-represented in normal compared to abnormal FLCr group (63.9% versus 31.3%). HLCr did not predict overall survival (OS) (log rank, p = 0.09), while an abnormal FLCr was associated with decreased OS (log rank, p = 0.03). The combined use of both ratios trended toward increased OS in the abnormal HLCr/normal FLCr group (log rank, p = 0.11; Wilcoxon, p = 0.04). On multivariate analysis, HLCr was not predictive of OS, whereas an abnormal FLCr was associated with shorter OS (HR = 1.7, p = 0.04). Conclusions : The HLC assay has potential as a supplemental test to quantify monoclonal protein in patients with normal FLCr results.