Thyroglobulin Antibody Blood Test: Normal Ranges, Causes & What Your Results Mean

What Is Thyroglobulin Antibody?

Thyroglobulin antibodies (TgAb) are autoantibodies directed against thyroglobulin — a large glycoprotein produced exclusively by thyroid follicular cells. Thyroglobulin is the precursor molecule from which thyroid hormones (T3 and T4) are synthesised and stored within the thyroid gland.

The presence of TgAb indicates that the immune system has mounted a response against thyroid tissue, a hallmark of autoimmune thyroid disease. TgAb is found in approximately 10–15% of the general population and is more common in women.

Why Is TgAb Tested?

• Autoimmune thyroid disease — TgAb is present in ~80% of Hashimoto's thyroiditis and ~50% of Graves' disease
• Thyroid cancer monitoring — TgAb can interfere with thyroglobulin tumour marker assays; must be measured alongside thyroglobulin for accurate cancer surveillance
• Goitre investigation — presence of TgAb with goitre suggests autoimmune aetiology
• Family screening — autoimmune thyroid disease clusters in families
• Pregnancy thyroid assessment — TgAb-positive women have higher risk of postpartum thyroiditis

Normal Ranges

Reference ranges vary significantly between assay manufacturers. Always compare with your laboratory's specific range.

What Does a Positive TgAb Mean?

• Hashimoto's thyroiditis — the most common cause of hypothyroidism in the UK; TgAb with TPO antibodies
• Graves' disease — TgAb present in ~50% of cases
• Differentiated thyroid cancer — TgAb presence makes thyroglobulin unreliable as a tumour marker
• Postpartum thyroiditis — transient thyroid dysfunction in 5–10% of women after delivery
• Other autoimmune conditions — type 1 diabetes, pernicious anaemia, lupus, rheumatoid arthritis
• Healthy individuals — found in 10–15% of euthyroid people, especially women; may indicate subclinical autoimmunity

What Does a Negative TgAb Mean?

• No thyroid autoimmunity detected — thyroid disease may still be present from other causes
• Useful for thyroid cancer monitoring — absence of TgAb means thyroglobulin is a reliable tumour marker

Managing Thyroid Autoimmunity

• Regular thyroid function monitoring — positive TgAb increases risk of future hypothyroidism; check TSH annually
• Selenium supplementation — 200 µg/day selenomethionine may reduce thyroid antibody levels (evidence strongest for TPO antibodies)
• Optimise vitamin D — deficiency is associated with higher rates of thyroid autoimmunity
• Gluten assessment — there is an association between coeliac disease and autoimmune thyroiditis
• Stress management — stress can trigger autoimmune flares
• If thyroid cancer — trending TgAb levels over time may serve as a surrogate tumour marker

When Should You Get Tested?

• You have been diagnosed with or suspected of having thyroid disease
• After thyroid cancer treatment, alongside thyroglobulin measurement
• Family history of autoimmune thyroid disease
• You have another autoimmune condition
• As part of a comprehensive thyroid antibody panel

Which Lola Health Tests Include TgAb?

Thyroglobulin antibodies are available as an add-on with any Lola Health blood test. For comprehensive thyroid assessment, combine with TSH, FT4, FT3, and TPO antibodies.