Novel extended reference range for serum kappa/lambda free light chain ratio in diagnosing monoclonal gammopathies in renal insufficient patients.

摘要

To the editor:We read with interest the articles by Wolff et al. [1] and McCudden et al. [2], where urine immunofixation electro-phoresis (IFE) test is compared to serum kappa/ lambda free light chain (FLC) assay in patients with monoclonal gammopathy [1] and where a case of hook effect in the serum FLC assay using the Olympus AU400e is described [2]. Such patients frequently have reduced renal function and proteinuria, because of their disease. These are confounding variables in the evaluation of FLC measurements. Consequently, the role of renal insufficiency in interpreting kappa/lambda FLC ratio must be thoroughly examined, because of possible false-positive results. The latter, an important parameter, was not investigated in any of the aforementioned papers.