Professional and Linguistic Assessments Board (PLAB) Practice Exam

Which antibodies are commonly found in Hashimoto's thyroiditis?

1. Anti-TPO (thyroid peroxidase)

2. Anti-thyroglobulin

3. Anti-TSH receptor

4. Anti-microsomal

The correct answer is: Anti-TPO (thyroid peroxidase)

In Hashimoto's thyroiditis, the primary antibodies that are characteristically elevated include anti-thyroid peroxidase (anti-TPO) antibodies. The presence of these antibodies is significant because they target the enzyme thyroid peroxidase, which is crucial for synthesizing thyroid hormones. High levels of anti-TPO antibodies are indicative of autoimmune activity against thyroid cells and are commonly used in clinical practice as biomarkers for Hashimoto's thyroiditis. While both anti-thyroglobulin and anti-microsomal antibodies can also be present in Hashimoto's thyroiditis, the most specific and commonly tested antibody associated with this condition in a variety of settings is anti-TPO. The anti-TSH receptor antibodies are more typically seen in Graves' disease, another autoimmune thyroid condition, emphasizing the difference in antibody profiles associated with specific thyroid disorders.