Results of the multicenter evaluation of the CEDIA Theophylline assay.

We report on the results of the multicenter evaluation of the CEDIA Theophylline assay on Boehringer Mannheim/Hitachi analyzers in 15 clinical laboratories in Europe and U.S.A. Main items of investigation were imprecision, recovery of control sera, interlaboratory survey and method comparisons using patient samples. Imprecision was found to be comparable to other routine methods. An advantage of the CEDIA assay can be seen in the good interlaboratory transferability of results. The new test has been shown to measure very accurately particularly by comparison with HPLC procedures revealing highly correspondent results. The reagent can be used up to one month using multiple recalibration. Due to its high practicability and reliability the CEDIA Theophylline assay can be recommended as a very suitable routine method for therapeutic drug monitoring on random access analyzers like Boehringer Mannheim/Hitachi analysis systems.

Results of the multicenter evaluation of the CEDIA Phenytoin assay.

Thirteen clinical evaluation sites in Europe and U.S.A. investigated the CEDIA Phenytoin assay on Boehringer Mannheim/Hitachi analyzers with respect to imprecision, recovery of control sera, interlaboratory survey, linearity and method comparisons using patient samples. The linear dose-response relationship up to 40 micrograms/mL was confirmed by all participants. Imprecision at therapeutic analyte concentrations equalled that of other routine methods. Recovery of controls was found in a +/- 6% range for target values assigned by the CEDIA assay. The good interlaboratory transferability of the CEDIA assay was confirmed with control material and human samples. The reconstituted reagent can be used up to one month using weekly recalibration. In method comparison studies good correlations to other routine methods were obtained. Results in analyte-free human sera did not deviate systematically from the zero-point. Thus, the accuracy in patient sera has been shown for the CEDIA Phenytoin assay.

Results of the multicenter evaluation of the CEDIA Phenobarbital assay.

The CEDIA Phenobarbital assay has been evaluated in twelve clinical laboratories in Europe and U.S.A. on Boehringer Mannheim/Hitachi analysis systems. The evaluation focused on the analysis of imprecision and accuracy. Within-run and between-day coefficients of variations of the new assay were comparable to those of established routine methods. As demonstrated in an interlaboratory survey study with controls and human sera, results obtained in different laboratories showed a good agreement. The CEDIA Phenobarbital assay measured very accurately, as particularly confirmed by comparison with HPLC. It can be recommended as a reliable and practicable test for monitoring of phenobarbital on Boehringer Mannheim/Hitachi analyzers used in routine clinical chemistry.

Results of the multicenter evaluation of the CEDIA cortisol assay.

The present paper describes the multicenter evaluation of the CEDIA Cortisol test for total cortisol. The observed linearity of the test was between 1.2 and 50 micrograms/dL cortisol. The limit of detection was calculated as 1.2/dL. Imprecision studies covering the diagnostically relevant range (5-20 micrograms/dL cortisol) yielded coefficients of variation between 1.7-8.9% (within-run) and 2.7-10.5% (between-day). An interlaboratory survey using 41 human samples and three control sera demonstrated that the new CEDIA Cortisol assay has a good interlaboratory transferability. Method comparison studies between the CEDIA Cortisol test and EIA, FIA, FPIA, and various RIAs yielded an acceptable level of agreement and concordant results in most cases. Low cross-reactivity of the antibody used in the new cortisol assay was observed with precursors or metabolites of cortisol. Especially, dexamethasone did not cross-react. However, prednisolone, 6-methylprednisone, and corticosterone showed cross-reactivities. No limitation by endogenous interferences was observed. The CEDIA Cortisol assay permits the precise, fast and sufficiently specific determination of cortisol. Furthermore, it offers the advantages of a non-radioactive assay and can be performed conveniently on Boehringer Mannheim/Hitachi analyzers in combination with routine clinical chemistry.