Thyroglobulin Antibody

CPT: 86800
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Synonyms

  • Antithyroglobulin Antibody

Special Instructions

This test may exhibit interference when sample is collected from a person who is consuming a supplement with a high dose of biotin (also termed as vitamin B7 or B8, vitamin H, or coenzyme R). It is recommended to ask all patients who may be indicated for this test about biotin supplementation. Patients should be cautioned to stop biotin consumption at least 72 hours prior to the collection of a sample.


Expected Turnaround Time

1 - 3 days


Related Documents


Specimen Requirements


Specimen

Serum


Volume

1 mL


Minimum Volume

0.3 mL (Note: This volume does not allow for repeat testing.)


Container

Red-top tube or gel-barrier tube


Collection

Separate serum from cells, and transfer specimen to a plastic transport tube.


Storage Instructions

Room temperature


Stability Requirements

Temperature

Period

Room temperature

14 days

Refrigerated

14 days

Frozen

14 days

Freeze/thaw cycles

Stable x3


Causes for Rejection

Gross hemolysis; gross lipemia


Test Details


Use

This test is used to detect and confirm autoimmune thyroiditis and Hashimoto thyroiditis.


Limitations

Thyroglobulin antibody results should be interpreted in light of the total clinical presentation of the patient, including symptoms, clinical history, data from additional tests, and other appropriate information.


Methodology

Immunochemiluminometric assay (ICMA)


Additional Information

Thyroglobulin antibody (TgAb) measurement is typically used in two clinical scenarios, in the assessment of autoimmunity and in the follow-up of patients treated for differentiated thyroid carcinoma (DTC).1-8 In thyroid autoimmunity, TgAb level can be increased. However, the presence of TgAb is not always pathogenic nor diagnostic, especially at very low levels. Because changes in TgAb levels can reflect changes in thyroid tissue mass, TgAb concentrations can also serve as a surrogate tumor marker for DTC recurrence and for monitoring changes in tumor mass in certain patients.1 A rising, or de novo appearance of TgAb may indicate recurrence, whereas a progressive decline suggests successful treatment.3 When present, TgAb interferes with thyroglobulin (Tg) measurement, causing falsely low or undetectable Tg immunometric assay values that can mask disease. Guidelines mandate that every Tg test have TgAb measured simultaneously and quantitatively by immunoassay. The propensity and magnitude of TgAb-Tg interference relates to both Tg and TgAb concentrations and the class of Tg method used.

The United States NHANES III survey reported a TgAb prevalence of approximately 10% for the general population, measured by competitive immunoassay.1 This study reported that 3% of subjects with no risk factors for thyroid disease had detectable TgAb without associated presence of thyroid peroxidase (TPO) antibodies.1 TgAb prevalence has been shown to be approximately twofold higher than normal for patients diagnosed with disseminated thyroid carcinoma (~20%).2,3 It has been suggested that low levels may represent "natural" antibody in healthy individuals or, alternatively, may represent underlying silent autoimmune thyroid disease.4 There is some debate over the clinical utility of serum TgAb measurement for assessing the presence of thyroid autoimmunity in areas of iodide sufficiency.4,5 In iodide-deficient areas, however, TgAb is believed to be useful for detecting autoimmune thyroid disease, especially for patients with a nodular goiter. TgAb measurements are also useful for monitoring iodide therapy for endemic goiter, since iodinated Tg molecules are more immunogenic. Sera samples were obtained in the United States for males <30 years of age following the criteria outlined by the National Academy of Clinical Biochemists (NACB) for establishing a normal reference range for thyroid tests.6,7 The screening criteria included serum TSH levels between 0.5 and 2.0 mIU/L, no personal or family history of thyroid disease, and absence of nonthyroid autoimmune disease. One hundred thirty-seven screened samples were tested, generating a 95% nonparametric upper reference limit below 4 IU/mL. Additionally, 519 samples were collected in the United States for both males and females ranging from 18 to 74 years of age. The screening criteria included serum TSH levels between 0.5 and 2.0 mIU/L, no personal or family history of thyroid disease, and absence of nonthyroid autoimmune disease. Of the 519 samples tested, 96% fell below 4 IU/mL.

Labcorp reports TgAb results above the limit of detection as elevated. The decision to employ this threshold is based on the fact that the presence of TgAb above the limit of detection is suggestive of the presence of thyroid tissue and can be a negative prognostic in patients treated for DTC. Also, the presence of any level of TgAb in cases where Tg testing is ordered causes the lab to employ an alternate method for that measurement; one that is not confounded by TgAb.


Footnotes

1. Hollowell JG, Staehling NW, Flanders WD, et al. Serum TSH,T(4), and thyroid antibodies in the United States population (1988 to 1994): National Health and Nutrition Examination Survey (NHANES III). J Clin Endocrinol Metab. 2002 Feb;87(2):489-499.11836274
2. Spencer CA, Takeuchi M, Kazarosyan M, et al. Serum thyroglobulin autoantibodies: Prevalence, influence on serum thyroglobulin measurement, and prognostic significance in patients with differentiated thyroid carcinoma. J Clin Endocrinol Metab. 1998 Apr;83(4):1121-1127.9543128
3. Gorges R, Maniecki M, Jentzen W, et al. Development and clinical impact of thyroglobulin antibodies in patients with differentiated thyroid carcinoma during the first 3 years after thyroidectomy. Eur J Endocrinol. 2005 Jul;153(1):49-55.15994745
4. Ericsson UB, Chrisensen SB, Thorell JI. A high prevalence of thyroglobulin autoantibodies in adults with and without thyroid disease as measured with a sensitive solid-phase immunosorbent radioassay. Clin Immunol Immunopathol. 1985 Nov;37(2):154-162.3930112
5. Nordyke RA, Gilbert FI, Miyamoto LA,Fluery KA. The superiority of antimicrosomal over antithyroglobulin antibodies for detecting Hashimoto's thyroiditis. Arch Intern Med. 1993 Apr 12;153(7):862-865.8466378
6. Thyroglobulin Antibody II on the Beckman Access Coulter [package insert]. Brea, Calif: Beckman Coulter Inc; 2011.
7. Demers LM, Spencer CA. Laboratory medicine practice guidelines: Laboratory support for the diagnosis and monitoring of thyroid disease. Clin Endocrinol (Oxf). 2003 Feb;58(2):138-140.12580927
8. Spencer C, Fatemi S. Thyroglobulin antibody (TgAb) methods - Strengths, pitfalls and clinical utility for monitoring TgAb-positive patients with differentiated thyroid cancer. Best Pract Res Clin Endocrinol Metab. 2013 Oct;27(5):701-712.24094640

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
006685 Thyroglobulin Antibody 8098-6 006706 Thyroglobulin Antibody IU/mL 8098-6

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