From the Guidelines
To check for thyroiditis, the main antibodies to test for are anti-thyroid peroxidase (anti-TPO) antibodies and anti-thyroglobulin (anti-Tg) antibodies, with anti-TPO being more predictive than anti-Tg according to a study from Sweden 1. When considering the diagnosis of thyroiditis, particularly in the context of autoimmune thyroid disease associated with diabetes, it's crucial to understand the role of these antibodies.
Key Points to Consider:
- Anti-TPO antibodies are more predictive of thyroid dysfunction than anti-Tg antibodies in multivariate analysis 1.
- The presence of thyroid autoantibodies is predictive of thyroid dysfunction, most commonly hypothyroidism, although hyperthyroidism can also occur 1.
- Thyroid function tests may be misleading if performed at the time of diagnosis due to the effects of previous hyperglycemia, ketosis, or ketoacidosis, and should be repeated after achieving metabolic stability and good glycemic control 1.
- Regular monitoring of thyroid function is recommended if antibodies are detected, even if thyroid hormone levels are initially normal 1.
Recommendations for Testing:
- Consider testing individuals with type 1 diabetes for anti-thyroid peroxidase and antithyroglobulin antibodies soon after diagnosis 1.
- Measure thyroid-stimulating hormone concentrations at diagnosis when clinically stable or soon after glycemic control has been established, and consider rechecking every 1–2 years or sooner if symptoms suggestive of thyroid dysfunction develop 1. Given the most recent and highest quality evidence from 2023 1, the focus should be on testing for anti-TPO and anti-Tg antibodies, with an emphasis on the predictive value of anti-TPO antibodies for thyroid dysfunction.
From the Research
Thyroid Antibodies to Check for Thyroiditis
The following antibodies are relevant to check for thyroiditis:
- Thyroid peroxidase antibodies (TPOAb) 2, 3, 4, 5, 6
- Thyroglobulin antibodies (TgAb) 2, 3, 4, 5, 6
- Thyroid-stimulating hormone (TSH)-stimulation blocking antibody (TSBAb) or TSH-receptor antibody (TRAb) 3
Prevalence of Antibodies in Thyroiditis
- TgAb prevalence is higher than TPOAb prevalence in patients with Hashimoto's thyroiditis and painless thyroiditis 2
- TPOAb and TgAb are both positively associated with inflammation and multiple symptoms in Hashimoto's thyroiditis patients 5
- The presence of TPOAbs is associated with a 2 to 4-fold increase in the risk of recurrent miscarriages and preterm birth in pregnant women 6