External quality assessment of free light chains

Free light chain tests are used in the diagnosis and monitoring of light chain-associated amyloidosis and in monoclonal gammopathies such as multiple myeloma. Plasma cells secrete either kappa or lambda free light chains into the bloodstream as a by-product of antibody production. In myeloma the proliferation of malignant plasma cells leads to an increase in free light chain levels.

The Specific Proteins EQA programme comprises 26 protein analytes, including free and total light chains, C-reactive protein, complement proteins, immunoglobulins and rheumatoid factor. The programme has been running for 15 years and is assessed bi-weekly in six-monthly cycles. Samples are liquid and stable to expiry when stored at 2–8°C.