From the Guidelines
Thyroid peroxidase antibodies should be tested in patients with symptoms of thyroid dysfunction, unexplained fatigue, or family history of thyroid disorders, as their presence indicates an autoimmune process affecting the thyroid gland and predicts future development of hypothyroidism. Testing for thyroid peroxidase antibodies is crucial in evaluating patients with suspected thyroid disease, as these antibodies are the most common marker for autoimmune thyroid disease, particularly Hashimoto's thyroiditis. According to the most recent study 1, autoimmune thyroid disease is the most common autoimmune disorder associated with diabetes, occurring in 17–30% of individuals with type 1 diabetes. The presence of thyroid peroxidase antibodies often predicts future development of hypothyroidism, with approximately 5% of TPO-positive individuals progressing to overt hypothyroidism annually 1. Some key points to consider when testing for thyroid peroxidase antibodies include:
- Testing is recommended when evaluating patients with symptoms of thyroid dysfunction, unexplained fatigue, or family history of thyroid disorders
- Positive TPO antibody results indicate an autoimmune process affecting the thyroid gland, even when thyroid function tests may still be normal
- The presence of these antibodies often predicts future development of hypothyroidism
- Regular monitoring of thyroid stimulating hormone (TSH) levels every 6-12 months is recommended for antibody-positive patients with normal thyroid function to detect early thyroid failure
- No specific treatment targets TPO antibodies directly; instead, management focuses on monitoring thyroid function and treating hypothyroidism with levothyroxine when it develops. In the context of diabetes, testing for thyroid peroxidase antibodies is particularly important, as autoimmune thyroid disease is common in individuals with type 1 diabetes, and the presence of thyroid autoantibodies is predictive of thyroid dysfunction 1.
From the Research
Thyroid Peroxidase Antibodies
- Thyroid peroxidase antibodies (TPOAb) are a type of autoantibody that plays a significant role in autoimmune thyroid disease, particularly in hypothyroidism 2, 3.
- Studies have shown that TPOAb are present in the majority of patients with spontaneous hypothyroidism, with a prevalence of over 99% 2.
- The presence of TPOAb has been associated with thyroid enlargement, and a statistically significant correlation has been observed between TPOAb and thyroglobulin antibodies (TgAb) 2.
Determinants of Thyroid Peroxidase Antibodies
- Female sex and current smoking have been identified as determinants of TPOAb positivity and detectability, respectively 4.
- Higher age and alcohol consumption have been associated with lower odds of TPOAb detectability 4.
- The clinical importance of detectable TPOAb levels is illustrated by the association with an increased mortality risk, mainly in men 4.
Clinical Implications of Thyroid Peroxidase Antibodies
- TPOAb have been recognized as a valuable marker for identifying systemic inflammation and autoimmune activity in subclinical hypothyroidism, particularly in anti-TPO-positive individuals 5.
- The integration of TPOAb and high-sensitivity C-reactive protein (hsCRP) into routine evaluation may help stratify subclinical hypothyroidism patients based on cardiovascular and metabolic risk, guiding early therapeutic interventions 5.
- Significant correlations have been observed between hsCRP and TSH, and between hsCRP and anti-TPO, in subclinical hypothyroidism patients with anti-TPO positivity 5.
Laboratory Diagnosis of Autoimmune Thyroid Disease
- Assay of anti-thyroperoxidase (TPO) antibodies should constitute the main test for the diagnosis of autoimmune thyroid diseases, using third-generation ultrasensitive methods 6.
- Assay of anti-thyroglobulin (Tg) antibodies may be limited to patients with suspect autoimmune thyroid disease and negative for anti-TPO antibodies, and patients undergoing thyroglobulin assay 6.