Traceability to a common standard for protein measurements by immunoassay for in-vitro diagnostic purposes.
BACKGROUND
There is a lot of confusion about the meaning of "measuring a protein in biological fluids" for in-vitro diagnostic purposes. This is due to a lack of understanding of metrological concepts and of acceptance of a pragmatic metrological concept for mixture analysis.


METHODS
We describe the metrological concepts that apply to measurement of proteins. We propose a pragmatic reference measurement system for protein analysis. We investigate the feasibility of the approach with TSH as example.


RESULTS
The reference measurement system for a protein should be viewed as a dynamic continuum from discovery to translation into an SI-component. A quasi surrogate component-mixture may be defined by recommendations for epitopes that immunoassays should recognize. The all-procedure trimmed mean is proposed as surrogate reference measurement procedure. Traceability is established by transfer of the IU of an WHO standard to a panel of commutable sera. Investigation of the TSH-example showed that the approach may be feasible.


CONCLUSIONS
The proposed pragmatic concept would be a major step towards traceability of protein measurements by immunoassay. It would allow a staged introduction of standardization during the continuum from discovery of a protein to full scientific understanding and transformation to the SI-unit.
Thienpont
Linda M
LM
Laboratory for Analytical Chemistry, Faculty of Pharmaceutical Sciences, Gent University, Gent, Belgium. linda.thienpont@ugent.be
Van Houcke
Sofie K
SK
D019963:Clinical Chemistry Tests / Q000379:methods / Q000592:standards*; D005240:Feasibility Studies; D006801:Humans; D007118:Immunoassay / Q000379:methods / Q000592:standards*; D011506:Proteins / Q000032:analysis* / Q000276:immunology; D012015:Reference Standards; D013972:Thyrotropin / Q000032:analysis / Q000276:immunology
D011506:Proteins; D013972:Thyrotropin