Evaluation of AutoDELFIA and access automated immunoassay systems for third generation assays for thyrotropin

We evaluated the technical performance of two new commercial automated immunoassay systems of third-generation assays for thyrotropin. The interassay CV was 2.8% for AutoDELFIA and 3.25% for Access at thyrotropin concentrations of approximately 1.3 mIU/l. The lower detection limits of the assays were 0.023 mIU/l for AutoDELFIA and 0.0096 mIU/l for Access, and the functional sensitivity for a CV of 20% was 0.027 mIU/l and 0.028 mIU/l, respectively. Sample to sample carry over was negligible (0.0016% for AutoDELFIA and 0.005% for Access). The range of linearity was acceptable for Access (102-115%) but not for low thyrotropin concentrations in AutoDELFIA (143% for a thyrotropin value of 0.48 mIU/l). Correlation between AutoDELFIA and Access was adequate (r = 0.999). We conclude that both automated immunoassays offer good reliability, practicability and performance characteristics.