Prediction and prevention of autoimmune thyroid disease
Prevention of autoimmune thyroid disease (AITD) might become feasible in the future.Preventive intervention requires accurate prediction. AITD frequently runs in families, and twin studies have shown that genes contribute to a large extent to the risk of Graves' hyperthyroidism (GH) and Hashimoto's hypothyroidism (HH). However, CTLA-4 and HLA genes confer only a small risk, and the nature of the polygenetic background remains largely unknown. The impact of environmental factors has mostly been evaluated in cross-sectional studies, and not in relation to genotypes.
The Amsterdam AITD cohort study was designed to evaluate environmental factors in relation to known genotypes in the pathogenesis of AITD in a population at risk, i.e. healthy 1st or 2nd degree female relatives of patients with proven GH or HH.Here we report on this cohort of 803 women who have been followed for five years.
At study entrance, although the subjects were in self-proclaimed good health, 3.6% had hypothyroidism (subclinical in 2.3%, overt in 1.3%), and 2% had hyperthroidism (subclinical in 1.6%, overt in 0.4%). Pregnancy was associated with an increased risk and estrogen use with a decreased risk for hyperthyroidism. Of the 759 euthyroid subjects, 24% had TPO-Ab; in this group stressful life events and daily hassles were not related to TPO-Ab, but smoking and estrogen use were associated with a lower risk of having TPO-Ab. The prevalence of Yersinia enterocolitica YOP IgG-Ab and IgA-Ab was higher in the 803 AITD relatives than in controls but not related to TSH or TPO-Ab, suggesting a higher rate of persistent Yersinia infection in AITD relatives.
During follow-up 51 subjects developed overt AITD (hyperthyroidism in 12, hypothyroidism in 39), at an annual rate of about 1.4% in the remaining population at risk.Recent studies report a fall in TPO-Ab concentration upon selenium supplements.Selenium medication in euthyroid TPO-Ab positive subjects may decrease the risk to develop AITD.