All patients had blood work showing stable thyroid hormone levels. The average follow up duration was 6-7 years for all patients. The researchers used tests that measure not just the presence and amount of antibodies, but also the effect of those antibodies on thyroid cells (stimulation, inhibition or neutral).
One year after diagnosis, TSH receptor antibody levels were detectable in 30 patients (45%) and 5 years after diagnosis, 15 (23%) still had detectable antibody levels. In all groups, the overall levels were lower on follow up than at diagnosis. However, the patients who had surgery had the greatest decreases and the patients who had radioactive iodine had the least decreases.
When looking at the functional activity of the antibodies in patients who still had detectable levels, the majority was of a stimulating type with only one patient had antibodies of the inhibitory type.
WHAT ARE THE IMPLICATIONS OF THIS STUDY?
The results of this study suggest that a change in the function of the thyroid antibodies from stimulating to inhibiting is not likely to be contributing to remission in patients who elect to take antithyroid medications to treat Graves’ disease. Although surgery seems to be the type of treatment that leads to the furthest reduction in antibody levels, the choice of treatment for patients should be individualized, taking into account patients preference, desire for future pregnancies, availability of experienced surgeons and clinical factors such as the presence of Graves’ eye disease.
This study is limited because it included a small amount of patients, and does not provide answers for example to the question whether the patients who still had stimulating antibodies present after years are more likely to recur. Thus, additional studies are needed to confirm these findings.
— Jessie Block-Galarza, MD