Graves’ and Hashimoto’s Thyroid Disease: Race and Ethnic Relationships

MedicalResearch.com Interview with:
Donald S. A. McLeod, FRACP, MPH
Department of Population Health,
QIMR Berghofer Medical Research Institute, Herston,
Queensland, Australia

MedicalResearch.com: What are the main findings of the study?

Dr. McLeod: We examined the incidence of Graves’ disease and Hashimoto’s thyroiditis by race/ethnicity among U.S. active duty service personnel aged 20-54 years over a 15-year period (more than 20,000,000 person years follow-up). Cases were identified by International Classification of Diseases, Ninth Revision, Clinical Modification codes.

In women, we found that Graves’ disease was almost twice as common among non-Hispanic black and Asian-Pacific Islander personnel compared with non-Hispanic white personnel.  While in men, non-Hispanic black and Asian-Pacific Islander personnel had over two-and-a-half times higher incidence compared with non-Hispanic white personnel. The opposite pattern existed for Hashimoto’s thyroiditis, with non-Hispanic white personnel having the highest incidence, and non-Hispanic black and Asian-Pacific Islander personnel the lowest incidence. Hispanic personnel did not have significantly different incidence compared to white personnel for either disorder.

MedicalResearch.com: Were any of the findings unexpected?

Dr. McLeod: The relationship between race/ethnicity and Graves’ disease had not previously been defined. What is particularly interesting is the apparent mirror image relationships between Graves’ disease and Hashimoto’s thyroiditis and race/ethnicity. These stark race differences in the increase of autoimmune thyroid disease raise the important question of why? If we can work this out, we may unlock the mechanisms of autoimmune thyroid disease, and potentially yield insights into other autoimmune disorders.

MedicalResearch.com: What should clinicians and patients take away from your report?

Dr. McLeod: In the clinic, this new knowledge adds to physician-patient discussions about why autoimmune thyroid disease might have occurred. Each new finding adds knowledge about the manner in which these common and important disorders develop, with the hope that we may one day prevent them.

MedicalResearch.com: What recommendations do you have for future research as a result of this study?

Dr. McLeod: Our study identifies an important new risk factor for Graves’ disease. The next key question is whether our findings represent a military-specific phenomenon, or can be generalised to the wider population. We hope to address this issue soon.

If these findings apply to the wider population, our current study can’t answer whether these differences are due to genetics, environmental exposures, or a combination of both. Further study needs to be carried out, to find the mechanisms of thyroid autoimmunity, as this will have the potential to lead to prevention of Graves’ disease and Hashimoto’s thyroiditis, and may also lead to crucial insights into other autoimmune disorders.

Citation:

Variation in Rates of Autoimmune Thyroid Disease by Race/Ethnicity in US Military Personnel