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Quantitative Analysis of Serum Free Light Chains
A New Marker for the Diagnostic Evaluation of Primary Systemic Amyloidosis

Roshini S. Abraham PhD, Jerry A. Katzmann PhD, Raynell J. Clark, A.R. Bradwell MD, Robert A. Kyle MD, Morie A. Gertz MD
DOI: http://dx.doi.org/10.1309/LYWM47K2L8XYFFB3 274-278 First published online: 1 February 2003


Primary systemic amyloidosis is a plasma cell dyscrasia characterized by the accumulation of excess free immunoglobulin light chains (FLCs) as amyloid. One of the diagnostic features of amyloidosis is the presence of circulating monoclonal FLCs in the serum and urine of the patients. The FLC usually is present in small amounts, and immunofixation is required for detection. A nephelometric method for quantitating FLCs in serum has been described using antibodies that recognize only FLC not bound to heavy chain. We describe a retrospective study using this quantitative FLC method for assessing monoclonal FLCs in 95 patients with amyloidosis. The sensitivity of nephelometric serum FLC measurements is particularly useful in patients with negative immunofixation results for serum, urine, or both. In addition, the FLC assay can be used for follow-up of patients with amyloidosis who have undergone stem cell transplantation.

Key Words:
  • Amyloid
  • Amyloidosis
  • Monoclonal light chains
  • Immunoglobulins
  • Stem cell transplantation
  • Monoclonal gammopathy
  • Nephelometry