From the Guidelines
Anti-thyroid peroxidase antibodies should be assessed in individuals with type 1 diabetes, as they are predictive of thyroid dysfunction, particularly hypothyroidism, with a study indicating that anti-thyroid peroxidase antibodies were more predictive than antithyroglobulin antibodies in multivariate analysis 1. When evaluating anti-thyroid peroxidase (anti-TPO) antibodies, it is essential to consider their role in autoimmune thyroid disease, which is the most common autoimmune disorder associated with diabetes, occurring in 17–30% of individuals with type 1 diabetes 1.
- The presence of anti-TPO antibodies is predictive of thyroid dysfunction, with 25% of children with type 1 diabetes having thyroid autoantibodies at the time of diagnosis 1.
- These antibodies are more predictive of thyroid dysfunction than antithyroglobulin antibodies, as indicated by a study from Sweden 1.
- Thyroid function tests may be misleading if performed at the time of diagnosis due to the effect of previous hyperglycemia, ketosis, or ketoacidosis, and should be repeated soon after a period of metabolic stability and achievement of glycemic targets 1.
- Subclinical hypothyroidism may be associated with an increased risk of symptomatic hypoglycemia and a reduced linear growth rate, highlighting the importance of monitoring thyroid function in individuals with type 1 diabetes 1.
From the Research
Anti-Thyroid Peroxidase Overview
- Anti-thyroid peroxidase (anti-TPO) antibodies are associated with autoimmune thyroid disease, particularly hypothyroidism 2.
- The presence of anti-TPO antibodies can be an indicator of thyroid dysfunction, even in individuals with normal thyroid-stimulating hormone (TSH) levels 3.
Prevalence of Anti-TPO Antibodies
- A study found that 18.6% of patients with high-normal TSH levels had positive anti-TPO antibodies, compared to 3% of those with low-normal TSH levels 3.
- Another study reported that the prevalence of anti-TPO antibodies was higher in females and had a racial predominance in Hispanics, although these differences were not statistically significant 3.
Clinical Significance of Anti-TPO Antibodies
- The presence of anti-TPO antibodies can help distinguish individuals at risk of developing true hypothyroidism, particularly those with high-normal TSH levels 3.
- However, the effect of antibody positivity on TSH reference intervals was found to be less than expected, and the exclusion of subjects with elevated thyroid antibodies had no significant impact on free thyroxine (FT4) reference intervals 4.
Relationship with Thyroid Disease
- Anti-TPO antibodies are commonly found in patients with autoimmune chronic lymphocytic thyroiditis, a common cause of hypothyroidism 2.
- The measurement of anti-TPO antibodies may be useful in the diagnosis and management of thyroid disease, particularly in individuals with high-normal TSH levels or symptoms suggestive of hypothyroidism 3.