Rapid, fully automated measurement of plasma homocyst(e)ine with the Abbott IMx analyzer

We have developed a totally automated fluorescence polarization immunoassay for homocyst(e)ine with no pretreatment or chromatographic steps. Comparison with four well-established chromatographic methods yielded r values ranging from 0.980 to 0.997 and slopes from 1.030 to 1.493. Inter- and intraassay CVs ranged from 0.0% to 8.0% and from 0.0% to 6.4%, respectively. Imprecision (CV) of measuring six plasma samples on three instruments ranged from 6.3% to 10.2%. The assay was linear for plasma samples diluted with buffer from 0 to 8-fold. Mean recovery of homocysteine added to two plasma samples was 97.1% and 99.9%. The assay exhibited almost no cross-reactivity towards cysteine and methionine, and a batch of 20 samples can be processed in 60 min.