Serum free light chain level increase precedes amyloidosis

(HealthDay)—Increased serum free light chains (FLCs) precede the presentation of immunoglobulin light chain amyloidosis (AL amyloidosis), according to a study published online July 14 in the Journal of Clinical Oncology.

To characterize monoclonal immunoglobulin (M-Ig) light chains before clinical presentation of AL amyloidosis, Brendan M. Weiss, M.D., from the University of Pennsylvania in Philadelphia, and colleagues evaluated prediagnostic sera from 20 cases with AL amyloidosis and 20 healthy controls matched for age, sex, race, and age of serum sample. They performed serum protein electrophoresis with immunofixation and serum FLC analysis on all samples.

The researchers detected M-Ig in 100 percent of cases and none of the controls (P < 0.001). Detectable M-Ig was seen in 100 percent of cases at less than four years before diagnosis; 80 percent of cases at four to 11 years; and 42 percent of cases more than 11 years before diagnosis. At all time periods, the median FLC differential (FLC-diff) was higher in cases than controls. A FLC-diff >23 mg/L was seen in 85 percent of cases and no controls (P < 0.001). In 84 percent of cases and 16 percent of controls, the FLC-diff level increased more than 10 percent per year (P < 0.001).

"Increase of FLCs, including within the accepted normal range, precedes the development of AL amyloidosis for many years," the authors write.