Anti-TPO antibodies

Antibodies against the enzyme the thyroid uses to make its hormones.

They are the marker of autoimmune thyroid disease, and they usually appear years before TSH starts to drift.

This is a yes-or-no finding rather than a number to chart: how high the titre goes says little about how the thyroid is doing, and treatment does not aim at bringing it down. A positive result with a normal TSH means the thyroid is worth watching, not treating.

Worth discussing one clearly positive result together with TSH.