Question

A 37-year-old female went to her physician because she felt constant anxiety. She had lost about 15 pounds in the last few months and felt that her eyes had begun to bulge from her face a bit. Upon examination, her thyroid gland felt enlarged and firm. Laboratory results indicated increased thyroid hormone levels. Anti-thyroid stimulating hormone receptor antibodies were detectable in her plasma.

• What autoimmune condition is most likely?
• How would the presence of anti-thyroid stimulating hormone receptor antibodies affect thyroid function?

Answer 1

The most likely autoimmune condition is Graves disease.

Anti-thyroid stimulating hormone receptor antibodies are pathophysiologic and clinical indicators in autoimmune thyroid diseases.

Antithyroid antibodies are autoantibodies that target one or more components of the thyroid gland  and can act as markers to help diagnose autoimmune thyroid conditions.

For example, thyroid stimulating hormone receptor antibodies ( TRab) are seen mostly in Graves disease.

The thyrotropin receptor (TSH receptor) is the antigen for TSH receptor antibodies (TRAbs).

TRAbs are grouped depending on their effects on receptor signalling;

activating antibodies (associated with hyperthyroidism),

blocking antibodies (associated with thyroiditis) and

neutral antibodies (no effect on receptor).

Activating TRAbs are characteristic of Graves' disease (autoimmune hyperthyroidism).

These antibodies bind to and activate the receptor.

These antibodies activate adenylate cyclase by binding to the TSH receptor.

This causes the production of thyroid hormones and subsequent growth and vascularisation of the thyroid.