What is the most sensitive test for detection of paraproteinemia?
Yes. That is correct. Most of you got it right. I think its about time that everyone starts using serum free light chains not only for detection but also for follow up in some of the paraproteinemia patients. The serum immunoglobulin-free light chain (FLC) assay measures levels of free and immunoglobulin light chains. Based on the Hematology Associations. there are three major indications for the FLC assay in the evaluation and management of multiple myeloma and related plasma cell disorders (PCD). In the context of screening, the serum FLC assay in combination with serum protein electrophoresis (PEL) and immunofixation yields high sensitivity( just serum free light chains and immunofixation is good enough and you can rule out a lot of your paraproteinemias), and negates the need for 24-h urine studies for diagnoses.
Just for context, a serum immunofixation might detect 50 fold increase in a specific light chain, the serum free light chains assay detects even a 10 fold increase; hence making it very sensitive test.
Second, the baseline FLC measurement is of major prognostic value in virtually every PCD. Third, the FLC assay allows for quantitative monitoring of patients with oligosecretory PCD, including AL Amyloidosis, oligosecretory myeloma and many patients who had previously been deemed to have non-secretory myeloma. In AL Amyloidosis patients, serial FLC measurements outperform PEL and immunofixation. In myeloma patients, although not formally validated, serial FLC measurements reduce the need for frequent bone marrow biopsies.
Check out the above linked reference for further reading.
For excellent reading: Read the Kidney in Plasma Cell Dyscrasias
The links below are also helpful:-