Serum immunoglobulin free light-chain measurement in primary amyloidosis: prognostic value and correlations with clinical features

Immunoglobulin free light chains (FLCs) are the precursors of amyloid fibrils in primary amyloidosis (AL). We studied the relationship between FLC levels and clinical features in 730 patients with newly diagnosed AL. The plasma cell clone was lambda in 72% patients, and kappa in 28% patients. kappa-AL had more GI tract and liver involvement, where as renal involvement was more with lambda-AL. While the overall survival (OS) was similar for kappa and lambda-AL, the median OS for those without an identifiable serum heavy chain was significantly shorter (12.6 vs 29.9 months; P = .02). The OS was shorter among those with a higher dFLC (involved FLC-uninvolved FLC; kappa > 29.4 mg/ dL or lambda > 18.2 mg/dL using median for cutoff); 10.9 vs 37.1 months; P < .001. In multivariate analysis, dFLC was independent of other prognostic factors. The type of light chain impacts the spectrum of organ involvement and the FLC burden correlates with survival in AL. (Blood. 2010;116(24):5126-5129)