THYROGLOBULIN ANTIBODIES

Code
902.8550
Name
THYROGLOBULIN ANTIBODIES
Category
None
Department
Send-Out
Start Date
Expiration Date
Synonyms
Anti-Tg; TgAb; Thyrog Abs
CPT Codes
86800
Site
SBMF
Reference Test
ATLAS Test Code

Specimen Information

Type

Gold, SST

Volume

1.0 ml

Transport Info

Refrigerated

Fasting Required?
False
Patient Instructions

Reference Range

0.0-40.0 IU/mL

Methodology

Quantitative Chemiluminescent Immunoassay (CLIA)

Clinical Significance

Primarily used to diagnose autoimmune thyroiditis.
Autoantibodies to thyroglobulin are found in many patients with autoimmune disorders of the thyroid gland. Thyroglobulin is a 660,000 MW glycoprotein composed of two subunits. It is a secretory product of only the thyroid gland and is present in the serum of normal individuals. The thyroid hormones thyroxine (T4) and triiodothyronine (T3) are synthesized from tyrosine residues of thyroglobulin in the thyroid epitheliel cell. Thyroglobulin itself is not biologically active, and composes about 75% of the total protein of the thyroid follicular colloid (lumen). T4 and T3 are only released after thyroglobulin is endocytosed and proteolytically degraded in the thyrocyte.Autoantibodies to thyroglobulin appear to result from the inheritance of a dominant Mendelian trait in women and reduced penetrance in men. The autoantibodies are polyclonal with no restriction of light-chain type or heavy-chain subclass. In addition, there is evidence that suggests that the levels of autoantibodies of any given isotype to specific epitopes may vary from individual to individual. The presence of TgAb have been reported in a number of autoimmune disorders. Autoimmune thyroiditis was first described by Hashimoto in 1912 and the goitrous form is now generally called Hashimoto’s thyroiditis. The generic term autoimmune thyroid disease would include Hashimoto’s thyroiditis, lymphocytic, postpartum, and silent thyroiditis, idiopathic (primary) hypothyroidism and Graves disease. TgAb may be present in unclear cases of suspected thyroid autoimmunity (where the TPOAb is negative). The detection of thyroid autoantibodies and the measurement of thyroid stimulating hormone (TSH) can be useful in determining the diagnosis and management of autoimmune thyroid disorders In autoimmune thyroid diseases, a broad spectrum of antibodies can be detected. Two of the most significant are thyroglobulin antibodies (anti-Tg) and thyroid peroxidase antibodies (anti-TPO). These antibodies are known to occur typically in autoimmune thyroiditis. The measurement of thyroglobulin antibodies is only relevant in cases where thyroid peroxidase antibodies are negative and an autoimmune thyroid disease is suspected. Thyroglobulin antibodies are elevated in 60 to 70% of the patients with Hashimoto's thyroiditis and primary myxedema, as well as in 20 to 40% of patients with Graves disease.

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