From the Guidelines
Thyroid antibodies are blood tests used to diagnose autoimmune thyroid disorders, with the most common tests being thyroid peroxidase antibodies (TPOAb), thyroglobulin antibodies (TgAb), and thyroid-stimulating hormone receptor antibodies (TRAb). These tests should be ordered when an autoimmune thyroid condition is suspected, such as Hashimoto's thyroiditis or Graves' disease, as indicated by the most recent study in 2024 1. Positive results indicate the presence of antibodies attacking the thyroid gland. The interpretation of these tests is as follows:
- TPOAb and TgAb: Elevated levels suggest Hashimoto's thyroiditis
- TRAb: Elevated levels suggest Graves' disease No specific treatment is needed for the antibodies themselves, instead, treatment focuses on managing thyroid function:
- For hypothyroidism (Hashimoto's): Levothyroxine replacement therapy
- For hyperthyroidism (Graves'): Antithyroid medications (methimazole or propylthiouracil), radioactive iodine, or surgery Regular monitoring of thyroid function (TSH, free T4) is essential for proper management, as emphasized in the 2022 study 2. Antibody levels may fluctuate over time but don't typically guide treatment decisions once the diagnosis is established. Understanding these antibodies helps explain the autoimmune nature of thyroid disorders and why long-term management is often necessary, as highlighted in the 2018 study 3. Some key points to consider when evaluating thyroid antibodies include:
- The presence of anti-TPO antibodies identifies an autoimmune etiology for thyroid dysfunction and predicts a higher risk of developing overt hypothyroidism, as noted in the 2004 study 4
- Thyroid function tests may be misleading if performed at the time of diagnosis due to the effect of previous hyperglycemia, ketosis or ketoacidosis, weight loss, etc., as mentioned in the 2022 study 2
- Subclinical hypothyroidism may be associated with an increased risk of symptomatic hypoglycemia and a reduced linear growth rate, as indicated in the 2022 study 2
- Hyperthyroidism alters glucose metabolism and usually causes deterioration of glycemic control, as noted in the 2018 study 3
From the Research
Definition and Types of Thyroid Antibodies
- Thyroid antibodies, also known as thyroid autoantibodies, are antibodies that are directed against the thyroid gland and are associated with autoimmune thyroid disease (AITD) 5, 6.
- There are three major types of thyroid antibodies: + Thyroid-stimulating hormone receptor antibodies (TRAb) + Thyroid peroxidase antibodies (TPOAb) + Thyroglobulin antibodies (TgAb) 5, 7.
Role of Thyroid Antibodies in Autoimmune Thyroid Disease
- Thyroid antibodies play a fundamental role in the diagnostic approach to AITD, which includes conditions such as Hashimoto's thyroiditis and Graves' disease 5, 6.
- TRAb are the hallmark of Graves' disease and are also predictors of response to disease treatment 5, 8.
- TPOAb and TgAb are associated with an increased risk of progression to hypothyroidism and can be used to identify individuals with thyroid autoimmunity 5, 7.
Detection and Measurement of Thyroid Antibodies
- Thyroid antibodies can be detected and measured using various assays, including enzyme-linked immunosorbent assay (ELISA) and radioimmunoassay (RIA) 7.
- The presence and titers of thyroid antibodies should be interpreted in light of the clinical and other biological characteristics of each patient 8.
Clinical Significance of Thyroid Antibodies
- Thyroid antibodies can precede the development of autoimmune thyroid disease by years and can be used as a predictive marker for disease onset 9.
- The presence of thyroid antibodies in apparently healthy individuals should not be neglected, as it may indicate an increased risk of developing autoimmune thyroid disease 9.