When this laboratory changed from Abbott to DPC equipment for immunoassay in
July 2001, initial evaluation suggested that theophylline results for
patient samples were approximately 25% higher on the Immulite 1000 compared
to AxSYM. This difference has subsequently been confirmed with comparisons
against Centaur and HPLC. However, the bias was not seen on spiked EQA
samples from UKNEQAS and Randox. Results for DPC control material were
within specification, and investigations by DPC showed no problems with the
calibrators, although they have been reluctant to investigate the problem
further. There are not many users of this method in the UK, but if any other
laboratory has experienced a similar problem I should be pleased to hear
from them, especially if they have investigated the reason for the
discrepancy.
Thank you
John Sale
Department of Biochemistry
Poole Hospital
England
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