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Thyroglob Ab, Quant (TGA)

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EPIC Test Name

THYROGLOBULIN AB

EPIC Code

LAB533

Specimen Requirements

serum
Minimum Volume:0.5 mL
Collection:Collect specimens using standard laboratory procedures.
Transport:Room Temperature ASAP
Stability:Room Temp: 4 days at 20-25 degrees C
Refrigerated: 4 days at 2-8 degrees C
Frozen: 2 months at -20 degrees C
Container:GOLD
Rejection Causes:Hemolysis,
Insufficient Sample Volume, lipemic samples

Methods

Immunoassay

Turnaround Time

SpecimenFrequency
serumdaily

Reference Ranges

Immunoassay
All RangeUnit
<115 IU/mLIU/mL

Clinical Indications

Thyroglobulin (Tg) is a tyrosin-rich glycoprotein, synthesized and stored in the follicular colloid of the thyroid gland. Main physiological role of Tg is in the storage and synthesis of thyroid hormones T4 and T3. Normally, Tg is not released into the circulation. Tg leakage into the blood stream can occur in certain pathological conditions, e.g., inflammation causing follicular destruction (thyroiditis and autoimmune hypothyroidism), hemorrhage (nodular goiter), or abnormally rapid growth of thyroid tissue such as Graves disease or follicular cell-derived thyroid neoplasms. The presence of Tg in the circulation can triger immue reaction to form autoantibodies against Tg or TgAb in some individuals. The same processes may also be responsible for the formation of anti thyroid peroxidase (TPO) antibodies.
Thyroglobulin Autoantibodies (TgAb) can be detected in patients with Autoimmune Thyroid Disease, e.g., about 30% of patients with Graves' disease and about 85% of patients with Hashimoto's Thyroiditis. Measurements of TgAb can be used in assistance to the diagnosis of these disorders. In patients with autoimmune hypothyroidism, 30% to 50% may have detectable TgAb, while 50% to 90% will have detectable anti-TPO autoantibodies. In some patients with Graves disease, both TgAb and anti-TPO autoantibodies can be seen.
Tg measurments are used in post-operation of thyroid cancer (differentiated follicular cell-derived thyroid carcinoma) removal. Tg should be undetectable or at very low level after the complete removal of the thyroid gland. It is worth noting that presence of TgAB interferes with Tg measurements using immunoassays.

Additional Information

TgAb results as determined using different methodologies may vary significantly, therefore, cannot be directly compared with one another.

Common Synonyms

Quantitative Thyroglobulin Antibody, TA

Performed

Lab
Chemistry - Downtown

Interpretative Information

• Presence of significant titers of TgAb or anti-TPO autoantibodies supports for a diagnosis of Graves disease in patients with thyrotoxicosis.
• Positive TgAb in patients with elevated serum thyrotropin (TSH) levels suggests the future development of hypothyroidism.
• Postpartum thyroiditis patients with persistently elevated TgAb levels may have an increased likelihood of permanent hypothyroidism.
• In neonatal patients with hypothyroidism, presence of TgAb or anti-TPO indicates occurrence of transplacental antibody transfer, especially to the patient whose mother has a history of autoimmune thyroiditis or detectable thyroid autoantibodies.
• In patients in post-operation of thyroid cancer removal, Tg at undetectable or very low level suggests the complete removal of the thyroid gland, such interpretation should be made with caution and knowledge of TgAb test results.

CPT

86800

LOINC

8098-6

References

1. Fröhlich E, Wahl R. Thyroid Autoimmunity: Role of Anti-thyroid Antibodies in Thyroid and Extra-Thyroidal Diseases. Front Immunol. 2017;8:521. Published 2017 May 9. doi:10.3389/fimmu.2017.00521
2. Kamath C, Adlan MA, Premawardhana LD. The Role of Thyrotrophin Receptor Antibody Assays in Graves’ Disease. J Thyroid Res 2012;2012:8 https://doi.org/10.1155/2012/525936
3. Sapin P, d'Herbomez M, Gasser F, Meyer L, Schlienger JL: Increased sensitivity of a new assay for anti-thyroglobulin antibody detection in patients with autoimmune thyroid disease. Clin Biochem 2003;36:611-6. doi: 10.1016/s0009-9120(03)00114-0
4. Baloch Z, Carayon P, Conte-Devolx B, Demers LM, Feldt-Rasmussen U, Henry J, et al. Laboratory Medicine Practice Guidelines. Laboratory support for the diagnosis and monitoring of thyroid disease. Thyroid 2003;13:45-67. PMID: 12625976
5. Algeciras-Schimnich A: Thyroglobulin measurement in the management of patients with differentiated thyroid cancer. Crit Rev Clin Lab Sci 2018;55:205-18. doi: 10.1080/10408363.2018.1450830
6. Frohlich E, Wahl R: Thyroid autoimmunity: Role of anti-thyroid antibodies in thyroid and extra-thyroidal diseases. Front Immunol. 2017;8:521. PMID: 28536577

Contact Information

Chemistry - Downtown: (315)464-4460
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