Serum levels of immunoglobulin free light chains in monoclonal gammopathy of undetermined significance and their contribution to stratification and monitoring

Czech version

Authors: T. Pika ¹; J. Minařík ¹; P. Lochman ²; J. Bačovský ¹; V. Ščudla ¹
Authors‘ workplace: III. interní klinika – nefrologická, revmatologická, endokrinologická, Lékařská fakulta Univerzity Palackého a Fakultní nemocnice Olomouc ¹; Oddělení klinické biochemie a imunogenetiky, Fakultní nemocnice Olomouc ²
Published in: Transfuze Hematol. dnes,17, 2011, No. 4, p. 177-181.
Category: Comprehensive Reports, Original Papers, Case Reports

Overview

Introduction.
Monoclonal gammopathy of undetermined significance (MGUS) is a potentially malignant condition associated with a certain degree of probable transformation into one of the malignant forms of monoclonal gammopathy (MG). Identifying possible predictive factors of malignant evolution is the focus of several research centres. Determining serum levels of free light chains (FLC) appears to be a relatively significant parameter, enabling the identification of persons at higher risk of malignant transformation.

The report aims to present our own experience with determining FLC serum levels in a group of individuals with MGUS. Group and results. The monitored group numbered 191 persons with MGUS. Abnormal κ or λ FLC levels were detected in 119 (62.3%), and pathological values of the κ/λ index in 106 (55.5%) patients. During the six years of monitoring, 11 (5.7%) persons in total experienced transformation into a malignant form of MG, which corresponds approximately to a transformation rate of 0.95%/year in the whole group. Using the stratification system for MGUS based on the combination of quantity, monoclonal immunoglobulin isotype and the κ/λ index value, there were 56 (29.3%) persons in the low-risk group, 87 (45.5%) in the low-intermediate risk group, 45 (23.6%) in the high-intermediate risk group, and only 3 persons (1.6%) in the high-risk group. The transformation percentage for the individual groups corresponded to 0 vs. 4.5 vs. 13.3 vs. 33.3% over the course of 6 years. MGUS evolution was associated with increasing FLC levels and a change in the κ/λ index.

Conclusion.
The survey results have confirmed the practical benefits of testing FLC serum levels in persons with MGUS, particularly the positive contribution to risk stratification with identification of MGUS high risk forms, allowing early detection of malignant evolution and immediate initiation of adequate treatment.

Key words:
monoclonal gammopathy of undetermined significance, multiple myeloma, immunoglobulin free light chains, risk stratification.

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