ABSTRACT
Primary systemic amyloidosis (AL) is a plasma cell dyscrasia (PCD) in which clonal plasma cells in the bone marrow produces a monoclonal protein that is amyloidogenic. After the histopathological diagnosis of amyloid deposition is made from a biopsy specimen, subsequent typing as AL amyloidosis relies upon the detection of the monoclonal light chain by serum or urine immunofixation electrophoresis, or bone marrow immunohistochemistry. The serum free light chain (FLC) assay was developed to measure the elevated levels of unbound light chains in the serum and urine of patients with PCD. This chapter compares the serum free light-chain immunoassay for the quantitation of free light chains to the standard assays for plasma cell disease in terms of sensitivity and specificity. The quantitative nature of the FLC assay is likely to have value in monitoring patients after treatment. Diagnosis of AL rests upon a panel of hematologic tests, and in some cases, genetic testing to exclude other forms of amyloidosis.
