Three Main Thyroid Antibodies
| Antibody | Full Name | Associated Disease | What It Does |
|---|---|---|---|
| TPO-Ab | Thyroid peroxidase antibody | Hashimoto's (+ sometimes Graves') | Attacks enzyme needed for thyroid hormone production |
| TgAb | Thyroglobulin antibody | Hashimoto's | Attacks thyroglobulin (thyroid hormone precursor) |
| TRAb / TSI | TSH receptor antibody / thyroid-stimulating immunoglobulin | Graves' disease | Stimulates TSH receptor → excess thyroid hormone |
Clinical Patterns
| Pattern | Antibodies | Likely Condition | TSH |
|---|---|---|---|
| High TPO-Ab + hypothyroid symptoms | TPO-Ab positive | Hashimoto's thyroiditis | High |
| High TRAb + hyperthyroid symptoms | TRAb positive | Graves' disease | Low |
| High TPO-Ab, normal TFTs | TPO-Ab positive | Euthyroid Hashimoto's (monitor annually) | Normal |
| Post-partum thyroid dysfunction | TPO-Ab positive | Post-partum thyroiditis | Fluctuating |
Monitoring After DiagnosisOnce Hashimoto's is confirmed, TPO antibody levels don't need serial monitoring — they don't guide treatment. What matters is TSH normalisation on levothyroxine.
Graves' Ophthalmopathy
TRAb-positive Graves' disease is associated with thyroid eye disease (exophthalmos, lid retraction, diplopia). TRAb levels correlate with eye disease activity. High TRAb at diagnosis or relapse warrants ophthalmology referral.
If I have TPO antibodies, do I need treatment?
Not necessarily. If thyroid function tests (TSH, Free T4) are normal, no medication is needed. Monitor TSH annually as approximately 5% per year progress to overt hypothyroidism.
Can thyroid antibodies disappear?
TPO antibodies can decrease over time but rarely disappear completely. Selenium supplementation (200 μg/day) has evidence for reducing TPO antibody levels in Hashimoto's, though clinical benefit is modest.
Are thyroid antibodies hereditary?
Yes. Autoimmune thyroid disease runs strongly in families. First-degree relatives have a significantly higher risk and should be screened with TSH.
What is the difference between Hashimoto's and Graves'?
Both are autoimmune but opposite: Hashimoto's destroys the thyroid → hypothyroidism (low metabolism). Graves' stimulates the thyroid → hyperthyroidism (high metabolism). Both confirm with specific antibodies.
Medical Disclaimer: This page is for general education only and does not replace professional medical advice. Always consult a qualified healthcare provider.