Quantification of serum free light chain kappa and lambda by the SPAPLUS analyser

Area of Science:

• Clinical chemistry
• Immunodiagnostics

Background:

• Accurate measurement of serum free light chains (FLC) kappa (κ) and lambda (λ) is crucial for diagnosing and monitoring monoclonal gammopathies.
• The SPAPLUS® system offers a turbidimetric method for FLC determination, necessitating comparison with established immunonephelometric assays like BNII®.

Purpose of the Study:

• To clinically assess the performance of the SPAPLUS® system for serum κ FLC and λ FLC determination.
• To compare the SPAPLUS® system against the BNII® system for FLC measurements and the κ/λ ratio.

Main Methods:

• Analysis of 126 serum specimens using both the SPAPLUS® (turbidimetry) and BNII® (immunonephelometry) analysers.
• Comparison of absolute values for serum κ FLC and λ FLC, and the FLC κ/λ ratio between the two methods.
• Evaluation of results in conjunction with patient clinical history.

Main Results:

• Regression analysis revealed no significant differences between SPAPLUS® and BNII® for κ FLC and λ FLC in normal and pathological ranges.
• Minor discrepancies in absolute light chain values were observed for some patients, potentially impacting clinical interpretation.
• Overall good concordance was found between the two FLC measurement methods.

Conclusions:

• The SPAPLUS® system demonstrates good agreement with the BNII® for serum FLC analysis.
• Consistent use of the same laboratory and method is recommended for serial monitoring of patients with monoclonal gammopathies.
• FLC results require interpretation alongside other laboratory data and patient diagnosis.