Risk of Thyroid Disease in Relatives
Patients with Hashimoto's Thyroiditis and Graves Disease
Mar 7, 2009
It’s long been known that family members of patients with autoimmune thyroid disease (AITD), both Graves’ disease and Hashimoto’s thyroiditis, frequently develop autoimmune thyroid disorders. In a recent study published in the August 2008 issue of Archives of Internal Medicine, the esteemed thyroidologist Wilmar Wiersinga and his colleauges from the Netherlands describe a method of predicting risk in female relatives by evaluating and scoring various factors.
The Study
Wiersinga and his team from the Department of Endocrinology and Metabolism at the Academic Medical Center in The Netherlands have developed a predictive score to assess thyroid disease risk in female relatives. The score, which is known as the Thyroid Events Amsterdam (THEA) score, has broad applications. Although further studies are recommended by the team, this score can be used to calculate the risk of progression to overt hyperthyroidism or hypothyroidism within 5 years of the subject’s initial evaluation.
The Risk Factors
A baseline assessment of female relatives of patients with AITD included tests for:
- TSH (thyroid stimulating hormone or thyrotropin)
- FT4 (free thyroxine)
- TPO (thyroid peroxidase) antibody levels
Subjects were also tested for the presence and levels of Yersinia enterocolitica antibodies (which show past gastrointestinal infection with this bacteria). In addition, information was gathered regarding family background, smoking habits, use of estrogen therapy, pregnancies, and exposure to high levels of iodine.
The Follow-Up
After the initial evaluation, subjects were evaluated annually for 5 years. The researchers looked for:
- overt hypothyroidism (defined at the time as a TSH greater than 5.7 mu/L and FT4 levels less than 0.72 ng/dl (range 0.72-1.-56) or
- overt hyperthyroidism (defined as TSH less than 0.4 mu/L or FT4 greater than 1.56 ng/dl)
Results
As many as 7.5 percent of female relatives of patients with an autoimmune thyroid disorder developed an overt AITD within 5 years. About 1.5 percent of the subjects evaluated developed a thyroid disease each year. Overall, 38 women became hypothyroid and 13 women became hyperthyroidism.
After evaluating the results, the researchers found that three risk factors stood out in predicting the development of overt thyroid disease. The independent risk factors that made the women more likely to develop an AITD included:
- TSH level with TSH greater than 2.0 mu/L increasing risk of hypothyroidism
- Family history, particularly having 2 relatives with Hashimoto’s disease
- Increased levels of TPO antibodies
These three risk factors were used to determine the Thyroid Events Amsterdam (THEA) score and relative risks were determined as low risk (0-7 score)l medium risk (8-10); high risk (11-15) and very high risk (16-21). After the study's conclusion, the researchers determined that:
- 2.7 percent of women with low risk developed thyroid disease within 5 years
- 14.6 percent of women with medium risk developed thyroid disease within 5 years
- 27.1 percent of high risk women developed thyroid disease within 5 years
- 76.9 percent of very high risk women developed thyroid disease within 5 years.
Source:
TG Strider, JG Tijssen, BE Wenzel, E Endert, and WM Wiersinga, Prediction of progression to overt hypothyroidism or hyperthyroidism in female relatives of patients with autoimmune thyroid disease using the Thyroid Events Amsterdam (THEA) score, Archives of Internal Medicine, Aug 11, 2008l 168(15)L 1657-1163.
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