[Usefulness of a free light chain immunoassay in serum for the diagnosis and the follow-up of monoclonal gammopathy].

PURPOSE: Monoclonal immunoglobulin free light chains (FLC) are present in the serum and urine of many patients with monoclonal gammopathies. In this review, we discuss the usefulness of serum FLC determination for diagnostic, prognostic and monitoring of multiple myeloma (MM), AL amyloidosis and monoclonal gammopathies of undetermined significance (MGUS).

CURRENT KNOWLEDGE AND KEY POINTS: Serum FLC assay is a useful laboratory test for management of light chain MM, non-secretory MM and AL amyloidosis. Currently, serum FLC testing cannot be recommended for monitoring intact immunoglobulin multiple myeloma. Even though serum FLC determination give a better risk stratification for MGUS, systematic serum FLC assay should not be used in routine because of high MGUS occurrence in the general population.

FUTURE PROSPECTS AND PROJECTS: Further prospective studies with large cohorts of patients should provide additional evidence for the role of serum FLC measurement in patients with intact immunoglobulin multiple myeloma.