From the Guidelines
The presence of Thyroid Peroxidase (TPO) antibodies is a significant marker for autoimmune thyroid disease and predicts a higher risk of developing overt hypothyroidism, with a risk of about 4.3% per year, as identified in a study published in JAMA in 2004 1. The clinical significance of TPO antibodies lies in their ability to indicate an autoimmune etiology for thyroid dysfunction.
- TPO antibodies are associated with Hashimoto's thyroiditis, an autoimmune condition that can lead to hypothyroidism.
- The presence of TPO antibodies can help diagnose autoimmune thyroid conditions before thyroid function becomes abnormal.
- Patients with positive TPO antibodies but normal thyroid function have a higher risk of developing hypothyroidism in the future.
- A more recent study published in Diabetes Care in 2022 found that TPO antibodies are also predictive of thyroid dysfunction in individuals with type 1 diabetes, with 25% of children with type 1 diabetes having thyroid autoantibodies at the time of diagnosis 1.
- The presence of TPO antibodies may also be associated with increased risk of miscarriage and pregnancy complications, and may be found in other autoimmune conditions like rheumatoid arthritis and lupus.
- While no specific treatment targets the antibodies themselves, their presence guides clinical decisions about thyroid hormone replacement therapy, especially in borderline cases.
- Regular monitoring of thyroid function is recommended for patients with positive TPO antibodies, even if their thyroid function is currently normal, to detect early development of hypothyroidism.
From the Research
Clinical Significance of Thyroid Peroxidase (TPO) Antibodies
The presence of TPO antibodies is a significant indicator of autoimmune thyroid disease, with studies showing a high correlation between TPO antibodies and thyroid microsomal antibodies 2. The clinical significance of TPO antibodies can be summarized as follows:
- TPO antibodies are a major autoantigen in autoimmune thyroid diseases, with a high prevalence in patients with hypothyroidism and hyperthyroidism 3, 4
- The presence of TPO antibodies is associated with an increased risk of developing hypothyroidism, particularly in euthyroid subjects with normal thyrotropin levels 3
- TPO antibodies can be used as a marker to identify individuals at risk of developing thyroid dysfunction, including those with a family history of autoimmune thyroid disease, pregnant women, and individuals with other autoimmune diseases 3, 5
- The measurement of TPO antibodies can be used to monitor the progression of thyroid disease and the response to treatment, with changes in antibody levels observed in response to treatment with thyroid hormones or antithyroid medications 6
Diagnostic Value of TPO Antibodies
The diagnostic value of TPO antibodies can be summarized as follows:
- TPO antibodies have a high sensitivity and specificity for the diagnosis of autoimmune thyroid disease, particularly Hashimoto's thyroiditis and Graves' disease 2, 6
- The presence of TPO antibodies can be used to distinguish between autoimmune and non-autoimmune forms of thyroid disease 6
- TPO antibodies can be used in combination with other diagnostic tests, such as thyroid ultrasonography and measurements of thyrotropin and thyroglobulin antibodies, to evaluate the extent of thyroid disease and monitor the response to treatment 4, 5
Association with Thyroid Disease
The association between TPO antibodies and thyroid disease can be summarized as follows:
- TPO antibodies are associated with an increased risk of developing hypothyroidism, particularly in euthyroid subjects with normal thyrotropin levels 3
- The presence of TPO antibodies is associated with thyroid enlargement and lymphocytic infiltration in euthyroid subjects 3, 4
- TPO antibodies are more frequently measured than thyroglobulin antibodies in patients with autoimmune thyroid disease, and are associated with a higher risk of developing hypothyroidism 4