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37.3.1. Overview of Freelite and Hevylite assays on the SPAPLUS

Chapter 37

37.3.1. Overview of Freelite and Hevylite assays on the SPAPLUS

Freelite and Hevylite kits supplied for the Binding Site SPAPLUS each contain sets of calibrator fluids that are used to generate calibration curves. These are then validated using two levels of kit-matched control fluids. Samples are initially measured at the standard programmed sample dilution, and if out of range, the instrument automatically re-measures the sample at the appropriate higher (1/100) or lower (1/1) dilution (Section 7.3). Very high level samples may require further manual offline dilutions.

For example, the range of reportable results for SPAPLUS Freelite κ and λ assays is 0.4 – 180,000 mg/L and 0.45 – 165,000 mg/L, respectively. Good analytical sensitivity of Freelite SPAPLUS assays was demonstrated by Matters et al.[149]. Performance characteristics of Freelite and Hevylite on the SPAPLUS are summarised in Table 37.2.

A particular advantage of the SPAPLUS Hevylite assays is their wide measuring range. In comparison with the Siemens BN™II, SPAPLUS assays require fewer dilutions to reach the upper limit of the reportable range. Measuring ranges are discussed further in Section 9.4.3.

Freelite Hevylite
κ λ IgGκ IgGλ IgAκ IgAλ IgMκ IgMλ
Range 4.0 - 180.0 mg/L 4.5 - 165.0 mg/L 1.9 - 40.0 g/L 0.92 - 29.5 g/L 0.18 - 11.2 g/L 0.16 - 10.4 g/L 0.2 - 5.0 g/L 0.18 - 4.5 g/L
Standard dilution 1+9 1+9 1+19 1+19 1+9 1+9 1+9 1+9
Sensitivity (neat assay dilution) 0.4 mg/L 0.5 mg/L 0.094 g/L 0.046 g/L 0.018 g/L 0.016 g/L 0.02 g/L 0.018 g/L
Assay time 15 min 15 min 15 min 15 min 15 min 15 min 15 min 15 min

Table 37.2. Performance characteristics of Freelite and Hevylite assays on the Binding Site SPAPLUS.


References

    • 1. Matters DJ, Showell PJ, Harding SJ, Carr-Smith HD, Smith LJ. Inter-batch variation and within batch precision of The Binding Site Freelite light chain assays. Clin Chem 2013;59:A-253a