Characterisation of an interference affecting the triiodothyronine measurement on two different immunoassays

ABSTRACT

We report a case of falsely elevated triiodothyronine (T3) due to anti-T3 antibody interference in two immunoassays (Cobas 8000 e602® module (Roche Diagnostics) and Architect® i2000 (Abbott)). The interference was investigated using various laboratory methods including the search for heterophilic antibodies, biotin detection and the polyethylene glycol precipitation of potential interfering macromolecules. The presence of anti-T3 autoantibodies was detected and measured by radioimmunoprecipitation. Our investigations confirmed the clinical suspicion of a falsely elevated free T3. No further explorations or unnecessary treatments were conducted for this patient after identification of the interference. This underlines the importance of implementing systematic analytical procedures in laboratories for the search of suspected interferences.

KEYWORDS:

• Free triiodothyronine
• interference
• triiodothyronine autoantibody
• immunoassay
• thyroid

Acknowledgments

The authors would like to express their gratitude to the laboratory of Cliniques Saint-Pierre Ottignies and the clinical laboratory of the CHU de Lyon for their collaboration in the investigation of this analytical interference.

Disclosure statement

No potential conflict of interest was reported by the authors.