Combined use of free light chain and heavy/light chain ratios allow diagnosis and monitoring of patients with monoclonal gammopathies: Experience of a single institute, with three exemplar case reports.

Monoclonal gammopathies are characterized by serum monoclonal component (MC) plus an intact immunoglobulin and a free light chain (FLC), or a combination of both. The measurement of FLC with Freelite is the standard practice recommended by International Myeloma Working Group guidelines. Recently, Hevylite heavy/light chains (HLC) assays were introduced to specifically target junctional epitopes between the heavy and light chains of intact immunoglobulins, allowing the independent quantification of the involved (MC) and uninvolved (polyclonal immunoglobulin background) HLC isotype.