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Abstract: SA-PO1089

Normal Serum Free Kappa-Lambda Light Chain Ratios in AL Amyloidosis - A Single Center Experience

Session Information

Category: Pathology and Lab Medicine

  • 1502 Pathology and Lab Medicine: Clinical

Authors

  • Seifter, Ari, Loyola University Medical Center, Maywood, Illinois, United States
  • Senthilkumar, Arouna, Loyola University Medical Center, Maywood, Illinois, United States
  • Kramer, Holly J., Loyola University Medical Center, Maywood, Illinois, United States
  • Vellanki, Kavitha, Loyola University Medical Center, Maywood, Illinois, United States
Background

Quantification of serum free light chains (FLC) is reported to be highly sensitive for diagnosis of primary systemic amyloidosis, with reported sensitivities of 90-100%. Although tissue diagnosis remains the gold standard for establishing definitive diagnosis, normal FLC ratios are often interpreted clinically as effectively ruling out amyloidosis. The aim of this study is to examine if our experience is different from the reported literature.

Methods

All patients who had serum FLC quantification and bone marrow biopsy at Loyola University Medical Center between the years 2007-2017 were analyzed in a retrospective chart review. A total of 1,270 patients were identified and 51 had a confirmed diagnosis of AL-amyloidosis. A FLC ratio of 0.26-1.65 was considered normal, consistent with past studies. Reported p-values were determined using a chi-squared test.

Results

Of the 51 patients with tissue diagnosis of AL amyloidosis, 45% had localized disease (confined to one organ) while 55% had systemic disease (more than one organ involvement). Serum FLC ratios were normal in 33% of the cases (17/51). 43% with localized disease had normal FLC ratios compared to 25% of patients with systemic disease (p=0.14) (Figure 1). 23 patients (45%) had renal involvement and 5 of the 23 had normal FLC ratios at presentation. Overall, 28/51 (55%) patients had a concomitant plasma cell dyscrasia confirmed on bone marrow biopsy. Patients with plasma cell dyscrasia were significantly less likely (14%) than those without a plasma cell dyscrasia (57%) to have a normal free light chain ratios (p=0.001) at presentation. Although patients with systemic disease were more likely to have an underlying plasma cell dyscrasia than those with localized disease, this result did not reach statistical significance (p=0.14).

Conclusion

When amyloidosis is clinically suspected, serum FLC quantification may be insufficient to rule out the diagnosis, leaving biopsy of affected organ(s) as the prevailing gold standard.

Funding

  • Clinical Revenue Support