From the Guidelines
High TPO antibody levels indicate an increased risk of developing hypothyroidism, and regular monitoring of thyroid function with TSH and free T4 blood tests is recommended, typically every 1-2 years 1. The presence of high TPO antibodies suggests an autoimmune process affecting the thyroid gland, most commonly Hashimoto's thyroiditis.
- If thyroid function is normal, no specific treatment is needed for the antibodies themselves.
- However, if hypothyroidism develops, treatment with levothyroxine will be necessary, starting typically at a low dose and adjusting based on follow-up blood tests.
- The presence of TPO antibodies increases the risk of developing hypothyroidism over time, and patients should be aware of this risk.
- Regular monitoring of thyroid function is crucial to detect any changes in thyroid function, and treatment should be initiated promptly if hypothyroidism is diagnosed.
- It is also important to note that the presence of TPO antibodies identifies patients at increased risk for thyroid autoimmunity, and patients with previously normal TSH levels may be rechecked every 1–2 years or obtained at any time the growth rate is abnormal 1. The evidence from the American Diabetes Association suggests that thyroid function tests should be obtained at any time clinical thyroid dysfunction is suspected and in any patient who has thyromegaly 1. While another study found that the presence of anti-TPO antibodies predicts a higher risk of developing overt hypothyroidism, the evidence was insufficient to recommend either for or against routine measurement of anti-TPO antibodies in patients with subclinical hypothyroidism 1. However, the most recent and highest quality study recommends regular monitoring of thyroid function in patients with high TPO antibodies 1.
From the Research
High TPO Antibody Levels
- High TPO antibody levels are associated with an increased risk of developing hypothyroidism, as indicated by studies 2, 3.
- A study published in 2016 found that patients with TPO-Ab levels >500 IU/ml showed a moderately increased risk of having elevated TSH levels compared to those below this threshold 2.
- Another study from 2005 suggested that TPO antibody titers above an assay-dependent cut-off are a clear risk factor for hypothyroidism, with an annual risk of 2.1% in TPO-positive women with normal thyrotropin levels 3.
Associations with Thyroid Function and Other Clinical Outcomes
- Elevated TPOAb levels have been associated with higher TSH levels, overt or subclinical hypothyroidism, and a lower mortality risk in the oldest old 4.
- A 2025 study found that anti-TPO and high-sensitivity C-reactive protein (hsCRP) are valuable markers for identifying systemic inflammation and autoimmune activity in subclinical hypothyroidism, particularly in anti-TPO-positive individuals 5.
- Vitamin B12 and vitamin D deficiencies have been found to be associated with autoimmune hypothyroidism, and there is a negative correlation between these vitamin levels and anti-TPO antibodies in patients with autoimmune hypothyroidism 6.
Clinical Implications
- Measuring TPO antibodies in euthyroid subjects can be used to identify subjects with increased risk for hypothyroidism, such as women who wish to become pregnant, those with an increased risk per se who are pregnant, patients with other autoimmune diseases, and subjects on certain medications 3.
- The integration of anti-TPO and hsCRP into routine evaluation may help stratify subclinical hypothyroidism patients based on cardiovascular and metabolic risk, guiding early therapeutic interventions 5.
- Vitamin D and vitamin B12 deficiency should be investigated at the time of diagnosis and periodically on follow-ups in patients with autoimmune hypothyroidism 6.