Document Detail

Defining the impact of individual sample variability on routine immunoassay of serum free light chains (sFLC) in multiple myeloma.
MedLine Citation:
PMID:  23286947     Owner:  NLM     Status:  MEDLINE    
Serum free light chain (sFLC) measurement has gained widespread acceptance and is incorporated into various diagnostic and response criteria. Non-linearity and antigen excess are the main causes of 'variability' in the measurement of sFLC using immunoassay, but the impact of these on measurement has been unclear. We performed a retrospective evaluation using a dilutional strategy to detect these phenomena. A total of 464 samples in 2009 and 373 samples in 2010 were analysed for sFLC. Non-linearity was detected in both high and apparently normal sFLC. Major non-linearity of more than twofold is common in high kappa (20·2%) and lambda (14·1%). It is less common in samples with apparently normal levels - kappa (6·4%) and lambda (9·5%). 9·4% of kappa and 15·5% of lambda showed antigen excess at screening dilutions. 34·4% of the samples had either non-linearity or antigen excess. We conclude that significant measurement variability is common in the measurement of sFLC. There is currently no reliable technique to detect non-linearity phenomena unless a serial dilution strategy is applied to every analysis. We recommend that laboratories routinely reporting sFLC results for clinical services need appropriate strategies for addressing these issues. Clinicians should be aware of these limitations in interpretation of sFLC assay for individual patients. Future guidelines should adopt action thresholds which are grounded firmly in test performance parameters.
S H K Murng; L Follows; P Whitfield; J A Snowden; K Swallow; K Green; R Sargur; W Egner
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Clinical and experimental immunology     Volume:  171     ISSN:  1365-2249     ISO Abbreviation:  Clin. Exp. Immunol.     Publication Date:  2013 Feb 
Date Detail:
Created Date:  2013-01-04     Completed Date:  2013-03-12     Revised Date:  2014-02-04    
Medline Journal Info:
Nlm Unique ID:  0057202     Medline TA:  Clin Exp Immunol     Country:  England    
Other Details:
Languages:  eng     Pagination:  201-9     Citation Subset:  IM    
Copyright Information:
© 2012 British Society for Immunology.
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MeSH Terms
Diagnostic Tests, Routine
Immunoassay / standards*,  statistics & numerical data*
Immunoglobulin Light Chains / blood*
Multiple Myeloma / blood*
Nonlinear Dynamics
Observer Variation
Reference Values
Retrospective Studies
Reg. No./Substance:
0/Immunoglobulin Light Chains

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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