Quantitative serum free light chain assay in the diagnostic evaluation of AL amyloidosis.
We compared a new serum immunoassay for quantitation of serum free light chains (FLC) with the conventional tests for clonal immunoglobulin production: bone marrow immunohistochemistry, serum immunofixation electrophoresis, and urine immunofixation electrophoresis. Serum samples from 169 patients with AL amyloidosis and 20 controls were examined. Elevated levels of kappa-FLC and lambda-FLC were found in 94% and 93% of patients with the respective clonal disease. However, false positive elevations of kappa-FLC and lambda-FLC were found in 30% and 44% of patients with clonal disease of the other light chain subtype. We found that the FLC level was a reliable test for the diagnosis of clonal disease when the FLC kappa:lambda ratio was abnormal and was comparable to the conventional tests in patients with AL amyloidosis. After a histologic tissue diagnosis of amyloidosis, determining the type as AL amyloidosis relies on a panel of hematologic tests to determine light chain clonality and the exclusion other forms of amyloidosis.
Akar
Harun
H
Amyloid Treatment and Research Program at Boston Medical Center, Boston University School of Medicine, Boston, MA, 02118, USA.
Seldin
David C
DC
Magnani
Barbarajean
B
O'Hara
Carl
C
Berk
John L
JL
Schoonmaker
Christopher
C
Cabral
Howard
H
Dember
Laura M
LM
Sanchorawala
Vaishali
V
Connors
Lawreen H
LH
Falk
Rodney H
RH
Skinner
Martha
M
D000328:Adult; D000368:Aged; D000686:Amyloidosis / Q000097:blood* / Q000175:diagnosis / Q000473:pathology; D006801:Humans; D007118:Immunoassay / Q000379:methods; D007145:Immunoglobulin kappa-Chains / Q000097:blood*; D007146:Immunoglobulin lambda-Chains / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009391:Nephelometry and Turbidimetry / Q000379:methods; D012680:Sensitivity and Specificity
D007145:Immunoglobulin kappa-Chains; D007146:Immunoglobulin lambda-Chains