The thyroid gland produces a large protein called thyroglobulin to produce and store thyroid hormones T3 (triiodothyronine) and T4 (thyroxine).

Thyroglobulin acts as a scaffold or container to store iodine and produce thyroid hormones that are then released into the bloodstream.

What is thyroglobulin antibody (TgAb)

Antibodies detect foreign proteins in the body. The body “codes” proteins it builds into your DNA so it can recognize it as “Self”. The body tags proteins as “Non-Self” when it detects a protein it didn’t build.

In other words, antibodies are trained to distinguish between proteins built by the body and foreign proteins.

Antibodies protect the body by attacking foreign proteins. Because the body produces thyroglobulin, antibodies would not attack it. A thyroglobulin antibody, however, is a type of antibody that does attack thyroglobulin as if it were a threat.

Thyroglobulin antibodies tell you if you have an autoimmune version of hypothyroidism (Hashimoto’s) or hyperthyroidism (Graves.)

What is thyroglobulin antibody levels in blood test

Thyroglobulin antibodies measure autoimmune activity in the thyroid. You must look at this number alongside other measures such as TSH, Free T4, TPO antibodies (TPOAb), etc. Just because you clouds in the sky it doesn’t mean it’s raining. Blood tests show results in one of four categories:

Normal/Negative (no autoimmunity indicated)

Borderline/Mildly Elevated (subclinical autoimmune activity)

Elevated/Positive (Suggests autoimmune thyroid disease)

High (Active or chronic autoimmune thyroiditis, Hashimoto’s)

The ranges for these results are measured in International Units per milliliter (IU/mL) and vary by the test done. Some tests will consider anything under 4 IU/mL as “normal/negative” and everything above as positive. Some older tests may go up as high as 40 IU/mL for “normal/negative” and anything above 40 IU/mL would be considered positive.

Your tests should show either negative or positive.

What is thyroglobulin antibody high

Your immune system produces antibodies that attack thyroglobulin proteins in your thyroid. When Thyroglobulin Antibody High shows up on your blood test (TgAb High or TgAb Positive), it indicates your immune system is reacting to thyroglobulin, suggesting autoimmune disease.

Newer labs consider anything greater than 4 IU/mL as high. Older labs may consider anything greater than 20 or 40 to be positive. Check the reference range provided by the lab to determine the threshold at which your levels are considered normal/negative or high/positive. The same number could mean something different depending on the reference range provided by the lab.

Examples:

Lab #1 TgAb: 12 IU/mL (Reference Range: <20 IU/mL) – Normal/Negative

Lab #2 TgAb: 12 IU/mL (Reference Range: <4 IU/mL) – High/Positive