Evaluation of a new chemiluminescent TSH-receptor-antibody (TRAB) microparticle immunoassay

Aims: To evaluate the performance of a new TRAb assay (Abbott). Methods: Precision was assessed at 3 levels of kit controls (3, 10, 30 IU/L). The Abbott Alinity i TRAb assay was compared to the Roche TSH-R assay on the Cobas e801. Healthy subjects (normal TSH and fT4) were also assayed with the Abbott TRAb assay. Analysis was done using MedCalc Statistical Software v20.027 (MedCalc, Ostend, Belgium). Results: Within-run precision was 5.1%, 1.9%, and 0.8% (claimed 4.8%, 1.8%, and 1.1%). Between-run precision was 6.5%, 2.6%, and 0.9% (claimed 5.2%, 2.0%, and 1.2%). AMR was verified from 1.1–47.9 IU/L (claimed 1.3–50.0 IU/L) with maximum deviation from linearity at 10.1%. LOQ (20% CV) = 0.7 IU/L. Passing Bablok analysis (Abbott = 1.216 Roche + 0.222) showed good agreement between the Roche and Abbott assays (spearman r= 0.96, 95% CI 0.931–0.977). Bland Altman analysis (n=50, TSH-R 1.1–40 IU/L), showed that the mean TRAb difference (Abbott–Roche) was 1.7 IU/L (range -4.0 to 7.4). TRAb in healthy subjects (n=25) was 0.9–3.2 (claimed <3.1 IU/L). Conclusion: These results support that the Abbott TRAb assay compares well with an established TRAb assay and is fit for purpose.