You asked for the antibody test (or your doctor finally ran it), and now you’re staring at two unfamiliar names and a number that looks alarmingly high. Let’s decode it calmly and clearly.
What antibodies are — and why these ones matter
In an autoimmune condition like Hashimoto’s, the immune system mistakenly makes antibodies against your own thyroid. There are two main ones:
- TPO antibodies (TPOAb) — antibodies against thyroid peroxidase, an enzyme your thyroid uses to make hormone.
- Thyroglobulin antibodies (TgAb) — antibodies against thyroglobulin, a protein your thyroid uses to store hormone.
When either is elevated, it signals that your immune system is actively targeting your thyroid (NIDDK, Hashimoto’s Disease).
What “high” means (and what it doesn’t)
- Reference ranges vary by lab.
- Antibodies can be high while your TSH is still normal. The attack often shows up in antibodies years before it shows up in TSH.
- The trend over time matters more than a single reading.
Can you actually lower them?
Yes. Clinically-dosed selenium has repeated, controlled evidence for reducing TPO antibodies in autoimmune thyroiditis — including a landmark trial where 200 mcg/day significantly lowered them (Gärtner et al., 2002), confirmed by a 2024 meta-analysis (Peng et al.).
A high antibody result isn’t a sentence. It’s finally seeing the real opponent clearly — which is the first step to doing something about it.