Effective May 8th, 2023, Clinical Pathology Laboratories (CPL) is pleased to announce a change in the method and analytic platform for Thyroglobulin Antibody (Anti-Tg) and Thyroid Peroxidase Antibody (Anti-TPO). The new methodology is electrochemiluminescence immunoassay (ECLIA).

The change in instrumentation and methodology will result in changes to reference range and the clinical reporting range of the two assays.

Reference Range Changes

Thyroglobulin AB < 4 IU/mL <=115 IU/mL
Thyroid Peroxidase AB < 9 IU/mL <= 34 IU/mL
Assay Current Reference Range New Reference Range

Clinical Reporting Range Changes

Thyroglobulin AB 1 - 2200 IU/mL 10 - 4000 IU/mL
Thyroid Peroxidase AB 1 - 900 IU/mL 9 - 600 IU/mL
Assay Current Clinical Reporting Range New Clinical Reporting Range

Important note:Thyroglobulin AB values determined on patient samples by different testing procedures cannot be directly compared with one another and can cause erroneous medical interpretations. Re-baselining of patients may be required in some cases, and will be offered by CPL at provider request. CPL will also maintain the current analytic platform and methodology for 180 days after the above effective date. Requests for re-baselining will be performed on current, retained specimens.  CPL retains specimens for 7 days from receipt at our laboratory.

Thyroglobulin (Tg) is produced in the thyroid gland and is a main component in the lumen of the thyroid follicle. In synergy with the enzyme thyroid-specific peroxidase (TPO), Tg has an essential function in the iodination of L-tyrosine and in the formation of the thyroid hormones T4 and T3.

Thyroid-specific peroxidase (TPO) is synthesized in the endoplasmic reticulum, where it is folded to its native state and undergoes core glycosylation, before being transported to the apical plasma membrane of thyrocytes.

The detection of anti-TPO and anti-Tg are considered diagnostic markers of autoimmune thyroid disorders. The prevalence of these two antibodies is high in patients with Graves’ disease and Hashimoto’s thyroiditis.

Thyroglobulin AB RFLX EIA vs LCMS 4447
Thyroglobulin AB 4516
Thyroid Peroxidase AB 4513
Thyroid Antibody Group (TPO + TG) 4610
Thyroglobulin, Quantitative and Antibody 4927
Autoimmune Antibody Profile 4268
ANA Autoimmune Profile 4521
FARR ANA Autoimmune Profile 4537
ANA Autoimmune Panel Reflex to FARR 4884
Thyroid Cascade Reflex 2832
Name Order Code


Fröhlich E, Wahl R. Thyroid Autoimmunity: Role of Anti-thyroid Antibodies in Thyroid and Extra-Thyroidal Diseases. Front Immunol. 2017 May 9;8:521. doi: 10.3389/fimmu.2017.00521. PMID: 28536577; PMCID: PMC5422478.

Ghosh R, Chatterjee S, Dubey S, Pandit A, Ray BK, Benito-León J. Anti-Thyroid Peroxidase/Anti-Thyroglobulin Antibody-Related Neurologic Disorder Responsive to Steroids Presenting with Pure Acute Onset Chorea. Tremor Other Hyperkinet Mov (N Y). 2020 Jul 8;10:19. doi: 10.5334/tohm.175. PMID: 32775033; PMCID: PMC7394228.