["Medicines and Healthcare products Regulatory Agency's (MHRA's) Medical Device Alert MDA/2004/048 described bias in some endocrine test results obtained on a few immunoassay platforms, particularly the Bayer Advia Centaur instrument, when using blood specimens collected into Becton Dickinson (BD) Vacutainer SSTII Advance tubes. As users of BD tubes and the Advia Centaur instrument, we addressed our concerns about the quality of the results that we had previously reported by undertaking an independent study.", 'We compared the results of 15 immunoassays performed on Bayer Advia Centaur using blood specimens collected into four different BD Vacutainer tubes (plain, old and newly released BD SSTII Advance, and BD PSTII).', 'Compared with plain tubes, old SSTII Advance tube results showed no bias for testosterone, CA15-3, follicle-stimulating hormone and folate assays, but gave a positive bias for cortisol and a negative bias for vitamin-B12. Compared with plain tubes, BD PSTII tubes gave no significant bias for thyroid function tests, prolactin, parathyroid hormone, and CA125, but gave a negative bias for steroid assays, and a positive bias for gonadotrophins. The results obtained using new BD SSTII Advance tubes were generally comparable with those on plain tubes.'] Does comparison of Bayer Advia Centaur immunoassay result obtained on samples collected in four different Becton Dickinson Vacutainer tubes?