Background: The Dade Behring Syva® EMIT (enzyme multiplied immunoassay
technique) method for the measurement of tacrolimus in whole blood was evaluated
against the Abbott IMx® microparticle enzyme immunoassay (MEIA) method. EMIT measures
tacrolimus colorimetrically, whereas MEIA measures the analyte using fluorimetry.
Both methods incorporate a protein precipitation step prior to measurement.
Method: Whole blood specimens were treated by two types of precipitation
technique followed by analysis for tacrolimus by either MEIA or EMIT on the Bayer
Advia 1650. Linearity and precision were assessed and correlation analysis performed
to evaluate the EMIT assay on the Bayer Advia 1650.
Results: The EMIT tacrolimus assay was linear over the concentration
range 0.0-22.0 µg/L; the limit of detection was 1.2 µg/L. Correlation between the
Syva EMIT and IMx tacrolimus assays was excellent (r = 0.959) and no
significant bias existed between the two methods (mean difference, δ = 0.221 µg/L).
Calibration data for the EMIT assay was stable for a period of 24-48 h on the Advia
between runs.
Conclusion: The Syva EMIT assay for the measurement of tacrolimus in
whole blood is suited for daily routine use on the Bayer Advia 1650.
