Endocrine Abstracts

Background and aims: The type 1 DM patients who are GAD antibody positive have more risk of autoimmune thyroid disease than who are negative. In patients with autoimmune thyroid disease there is a significantly increased risk of anti-pancreatic autoimmune response as shown by increased GAD antibody positivity compared to normal population. However, the linkage between IA2 and thyroid autoimmunity is evaluated in one studied. Our aim is to evaluate the frequency of presence of anti-GAD antibody and IA2 in a Graves’ disease population.

Patients and methods: A total of 53 patients with newly-diagnosed Graves’ disease were included in this study of whom % 71.7 (n=38) were female (mean age=45.3) and % 28.3 (n=15) were male (mean age=41.2). The fasting plasma glucose measurements of all of the patients were normal. The GAD antibody, IA2 antibody, TSH receptor antibody and anti-TPO levels were studied by ELISA technique.

Results: There were 3 patients (2 female and 1 male) positive for GAD antibody (% 5.7) while 5 patients (4 female and 1 male) were positive for IA2 antibody (% 9.4). All of the patients with IA2 antibody positivity were also positive for TSH receptor antibody while only 2 of the GAD antibody positive patients had TSH receptor positivity. None of the patients revealed co-positivity for GAD and IA2 antibodies.

Conclusion: Our findings suggest that there was a unique population in autoimmune thyroid patients who presented with only IA2 positivity and without GAD antibodies. We also found that Graves’ disease patients have increased co-positivity of TSH receptor antibodies with IA2 compared with co-positivity with GAD. Further long term follow up are required to evaluate the clinical significance of IA2 positivity in this patient group