Performance characteristics of the Beckman Coulter UniCel DxI 800 TSH (3rd IS) assay

Introduction: Beckman Coulter recently reformulated their commercial TSH assay with primary calibration to the World Health Organization 3rd TSH international standard. An extensive evaluation of the performance characteristics for this assay was completed.

Methods: Intra-day and inter-day precision was evaluated using 3 concentrations of commercial quality control material. Linearity, reportable range, stability, sensitivity and susceptibility to common inferences were determined using pooled patient specimens. Inter-assay variability was assessed across 5 different platforms (n=47 patient specimens).

Results: Intra-day and inter-day CVs were <10% at all concentrations evaluated. The LOQ, LOD and LOB were 0.0047μIU/ml (10% CV), 0.0012μIU/ml and 0.0005μIU/ml, respectively. Variable bias was observed for the TSH3 assay when evaluated against the previous generation assay and other platforms, but overall TSH3 gave comparable results.

Conclusions: The TSH3 assay for UniCel DxI 800, is precise, highly sensitive and comparable to the previous generation assay. The assay is acceptable for clinical testing.