Antithyroglobulin Antibody Test

Test Description


Thyroglobulin is a thyroid glycoprotein that has a role in the synthesis of triiodothyronine
(T3) and thyroxine (T4). In some types of thyroid disorders, thyroglobulin may
escape from the thyroid gland. Once liberated, these substances appear as antigens
to the body. In response, the body produces antibodies against the thyroglobulin,
leading to inflammation and destruction of the thyroid gland. Antithyroglobulin
antibodies are present in the majority of patients diagnosed with Hashimoto’s thyroiditis.
The most dilute serum in which antithyroglobulin antibodies are detected
is called the titer.

Normal Values   Titer <1:100


Possible Meanings of Abnormal Values

Increased

Autoimmune hemolytic anemia
Diabetes mellitus Type 1
Granulomatous thyroiditis
Hashimoto’s thyroiditis
Hyperthyroidism
Juvenile lymphocytic thyroiditis
Myasthenia gravis
Myxedema
Nontoxic nodular goiter
Pernicious anemia
Primary hypothyroidism
Rheumatoid arthritis
Sjögren’s syndrome
Systemic lupus erythematosus
Thyroid autoimmune diseases
Thyroid cancer
Thyrotoxicosis

Contributing Factors to Abnormal Values

• Drugs that may increase antithyroglobulin antibody titers: oral contraceptives.

Interventions/Implications

Pretest
• Explain to the patient the purpose of the test and the need for a blood sample to be drawn.
• No fasting is required before the test.

Procedure

• A 7-mL blood sample is drawn in a red-top collection tube.
• Gloves are worn throughout the procedure.
Posttest
• Apply pressure at venipuncture site. Apply dressing, periodically assessing for continued
 bleeding.
• Label the specimen and transport it to the laboratory.
• Report abnormal findings to the primary care provider.

Clinical Alert                       

• This test is usually performed in conjunction with the antimicrosomal antibody
   test.
• If present in the mother, antithyroglobulin antibody can increase the risk of
  hypothyroidism or hyperthyroidism in the fetus or newborn