Bulletin:Thyroglobulin, Thyroglobulin Antibody, and Thyroid Peroxidase Antibody Testing

“Quality in Laboratory Diagnosis”

A Publication of Warde Medical LaboratoryIssue Number 28, Volume 4, 2018

The Warde Report Volume 28 Issue 4, 2018

Bulletin: Thyroglobulin, Thyroglobulin Antibody, and Thyroid Peroxidase Antibody TestingWilliam G. Finn, MD, Medical Director, Warde Medical Laboratory

Effective October 23, 2018, methodology for the Thyroglobulin (THY), Thyroglobulin Antibody (TGAB), and Thyroid Peroxidase Antibody (TPOAB) tests changed from Siemens Immulite 2000 to Beckman Access DXI.

This change in technology will allow us to fulfill a frequent client request for greater sensitivity in Thyroglobulin monitoring, with the lower limit of our reportable Thyroglobulin detection range moving from 1 ng/mL to 0.2 ng/mL. As with any change in tumor marker methodology, however, quantitative results obtained from the previous Immulite platform may not be directly comparable to the quantitative result obtained from the DXI platform, and this change will involve an update in Thyroglobulin reference ranges.

As a result of this platform change, there will also be an update in the reference ranges for Thyroglobulin Antibody and Thyroid Peroxidase Antibody tests. Published data indicate that, although all commercially available TGAB and TPOAB antibody assays show good analytical performance relative to WHO reference standards, there is well documented method-to-method variation.(1) Results from the Immulite to the DXI should be compared based on the negative or positive interpretation of these antibody values.

More recent generations of technology have substantially improved harmonization between methods,(2) and our in-house validation showed good concordance for positive and negative results for these assays, but as noted above, any two methods for this type of testing may not be directly interchangeable, and a small number of “high negative” samples from the previous Immulite platform may test as “low positive” on the new DXI.

References:

1. La’ulu SL, Slev PR, Roberts WL: Performance char-acteristics of 5 automated thyroglobulin auto-antibody and thyroid peroxidase autoantibodyassays. Clinical Chemica Acta 2007; 376:88-95.

2. D’Aurizio F, Tozzoli R, Villalta D, et al: Immunoassayof thyroid peroxidase autoantibodies: diagnosticperformance in automated third generation meth-ods. Clin Chem Lab Med 2015; 53(3):415-421.

William G. Finn, M.D., Medical Director Chadi Filfili, MS, MBA, CPH, CBSP, Director of Laboratory Operations

Direct Correspondence to:

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