Evaluation of the DPC IMMULITE 2000 assay for total homocysteine in plasma

The present report describes an evaluation in three laboratories of the completely automated total homocysteine immunoassay adapted to the IMMULITE 2000 from DPC. The precision depended on the control materials used, but with quality control materials and patient samples imprecisions were found to be in the range of 5.3 to 6.1% and 5.4 to 6.0%, respectively. Dilution experiments proved the assay to be linear and correlations with HPLC and GC-MS methods were close (r=0.98 and 0.97, respectively). In addition, the samples from the Nordic program for external quality assessment of methylmalonic acid and homocysteine for 2000 were assayed in the three laboratories. Imprecision evaluated from these samples was 5.3% and the recovery of the added L-homocystine was equivalent to the mean recovery of the 58 participants in the program. The precision is close to the quality goals. In conclusion, the method is an attractive alternative when coping with an increasing number of requests for the analysis of total homocysteine.