Evaluation of the N Latex free light chain assay in the diagnosis and monitoring of AL amyloidosis

Mollee, Peter, Tate, Jill and Pretorius, Carel J. (2013) Evaluation of the N Latex free light chain assay in the diagnosis and monitoring of AL amyloidosis. Clinical Chemistry and Laboratory Medicine, 51 12: 2303-2310. doi:10.1515/cclm-2013-0361

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Author Mollee, Peter
Tate, Jill
Pretorius, Carel J.
Title Evaluation of the N Latex free light chain assay in the diagnosis and monitoring of AL amyloidosis
Journal name Clinical Chemistry and Laboratory Medicine   Check publisher's open access policy
ISSN 1434-6621
1437-4331
Publication date 2013-12-01
Year available 2013
Sub-type Article (original research)
DOI 10.1515/cclm-2013-0361
Open Access Status File (Publisher version)
Volume 51
Issue 12
Start page 2303
End page 2310
Total pages 8
Place of publication Berlin, Germany
Publisher Walter de Gruyter GmbH
Language eng
Formatted abstract
Background: We compared a novel assay for free light chain (FLC) quantitation based on monoclonal antibodies (N-Latex, Siemens, Germany) to the established polyclonal antibody-based assay (Freelite™, The Binding Site, UK) in AL amyloidosis.

Methods: Sixty-two diagnostic samples were analysed on a BNII nephelometer, 32 of which also had a post-treatment sample.

Results: In the diagnostic samples: for AL of κ type, the median involved FLC (iFLC) was significantly lower by the N-Latex assay (289 vs. 667 mg/L, p=0.0002) whereas for λ AL the values were similar (148 vs. 161 mg/L, p=0.84). Measurable disease, defined as a difference between involved and uninvolved FLC (dFLC) >50 mg/L was present in 82% by the N-Latex assay compared to 89% by the Freelite™ assay. For diagnostic sensitivity, the FLC ratio was normal in 21% (95% CI 12%-33%) and 15% (95% CI 7%-26%) of patients by the N-Latex and Freelite™ assays, respectively. The combination of serum and urine immunofixation electrophoresis with either FLC assay allowed identification of the amyloidogenic clone in 98% producing comparable sensitivity. For the monitoring samples the median reduction in dFLC was 68% for the N-Latex assay and 77% for the Freelite ™ assay (p=0.04). This led to some differences in assigning response categories. Partial response as assigned by both assays predicted overall survival (N-Latex p=0.0015, Freelite™ p=0.022).

Conclusions: There are differences between FLC as measured by the N-Latex and Freelite™ assays, but overall the two assays have similar diagnostic sensitivity. Disease response calculated by both assays predicts survival but more clinical validation is required.
Keyword AL amyloidosis
Diagnosis
Free light chain assay
Monitoring
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2014 Collection
School of Medicine Publications
 
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