Evaluation of the Abbott IMx ultrasensitive II hTSH immunometric assay in three European centres: a comparison with established commercial immunometric assays for thyrotropin.

The Abbott Ultrasensitive II hTSH assay was evaluated in three European centres and its performance compared with its predecessor and with commercially available kits. A total of 408 individuals was included in the study (140 euthyroid, 116 hyperthyroid and 86 hypothyroid subjects, as well as 26 patients with non-thyroidal illness and 30 patients with thyroid cancer). The kit was evaluated for (im)precision and analytical and functional sensitivity according to ECCLS-Guidelines. The analytical sensitivity lay between 0.004 and 0.013 mU/1, the mean value being 0.008 mU/1, results being from 12 runs. The functional sensitivity gave a coefficient of variation below 20% at a concentration of 0.05 mU/1 under routine conditions. Inter-assay precision was less than 7% at 0.25 mU/l (range 5.3-6.8%), less than 6% at 6 mU/l (range 4.0-5.2%) and less than 9% at 30 mU/l (range 6.5 - 8.7%). Intra-assay (im)precision was not calculated as the Abbott IMx is designed to run on singlicate determinations.