PMID- 22998393
OWN - NLM
STAT- MEDLINE
DCOM- 20130118
LR  - 20191210
IS  - 1600-0609 (Electronic)
IS  - 0902-4441 (Linking)
VI  - 89
IP  - 6
DP  - 2012 Dec
TI  - Clinical and preclinical validation of the serum free light chain assay: 
      identification of the critical difference for optimized clinical use.
PG  - 458-68
LID - 10.1111/ejh.12013 [doi]
AB  - OBJECTIVES: The use of the assay for the measurements of free light chains in 
      serum (sFLCs) is increasing. However, there are technical limitations that 
      potentially affect the use in serial measurements. We need further knowledge on 
      the standards of analytical precision, the utility of conventional 
      population-based reference values and the critical difference (CD) between serial 
      results required for significance. To answer these questions, the biological 
      variation must be known. METHODS: We determined the biological variation in 
      healthy individuals and patients with plasma cell dyscrasia (PCD). We assessed 
      the imprecision of the analysis in use from FreeLite. We determined the 
      reference interval (RI) in 170 healthy individuals. RESULTS: The biological 
      variation is identical for healthy individuals and patients with PCD. The 
      imprecision of the sFLC analysis cannot fulfil the desirable performance 
      standards for a laboratory test, but are within the manufacturer's +/-20% variation 
      for quality control samples. RI showed a significant increase for kappa FLC and kappa/lambda 
      ratio with age, but not for lambda. Critical difference was calculated to be 24% and 
      23% for kappa and lambda, respectively. CONCLUSIONS: We suggest the use of an 
      age-dependent RI. When monitoring patients with PCD, their own former results are 
      the best reference, and knowledge on CD is a valuable tool, which we describe for 
      the first time. Also, it challenges the recently proposed International Myeloma 
      Working Group 'paraprotein relapse criteria', recommending an increase of more 
      than 25% in the involved FLC to indicate the need for initiation of retreatment. 
      We recommend revision of this criterion.
CI  - (c) 2012 John Wiley & Sons A/S.
FAU - Hansen, Charlotte T
AU  - Hansen CT
AD  - Department of Haematology, Odense University Hospital, Odense, Denmark.
FAU - Munster, Anna-Marie
AU  - Munster AM
FAU - Nielsen, Lars
AU  - Nielsen L
FAU - Pedersen, Per
AU  - Pedersen P
FAU - Abildgaard, Niels
AU  - Abildgaard N
LA  - eng
PT  - Journal Article
PT  - Validation Study
DEP - 20121016
PL  - England
TA  - Eur J Haematol
JT  - European journal of haematology
JID - 8703985
RN  - 0 (Immunoglobulin kappa-Chains)
RN  - 0 (Immunoglobulin lambda-Chains)
SB  - IM
MH  - Adult
MH  - Age Factors
MH  - Aged
MH  - Case-Control Studies
MH  - Female
MH  - Humans
MH  - Immunoassay/*standards
MH  - Immunoglobulin kappa-Chains/*blood
MH  - Immunoglobulin lambda-Chains/*blood
MH  - Male
MH  - Middle Aged
MH  - Multiple Myeloma/*blood/diagnosis
MH  - Nephelometry and Turbidimetry/*standards
MH  - Paraproteinemias/*blood/diagnosis
MH  - Reference Values
MH  - Reproducibility of Results
MH  - Sensitivity and Specificity
EDAT- 2012/09/25 06:00
MHDA- 2013/01/19 06:00
CRDT- 2012/09/25 06:00
PHST- 2012/09/13 00:00 [accepted]
PHST- 2012/09/25 06:00 [entrez]
PHST- 2012/09/25 06:00 [pubmed]
PHST- 2013/01/19 06:00 [medline]
AID - 10.1111/ejh.12013 [doi]
PST - ppublish
SO  - Eur J Haematol. 2012 Dec;89(6):458-68. doi: 10.1111/ejh.12013. Epub 2012 Oct 16.