Involvement of stress in the pathogenesis of autoimmune thyroid disease: a prospective study.

BACKGROUND: An association between stress and autoimmune thyroid disease (AITD) (especially Graves' hyperthyroidism) has been reported, but all studies so far on this topic have been retrospective.

OBJECTIVE: To evaluate prospectively the relationship between stress and (i) de novo occurrence of thyroid antibodies and (ii) development of overt autoimmune hyper-/hypothyroidism.

STUDY DESIGN: Two nested case-control studies in a prospective cohort of 790 euthyroid women who were 1st or 2nd degree relatives of AITD patients. Follow-up was five year, with annual assessments including questionnaires on stressful life events, daily hassles, and mood. In study A, cases were subjects who developed TPO-Ab but remained euthyroid during follow-up (called event). In study B, cases were subjects who developed overt hypothyroidism (TSH>5.7 mU/l and FT4<9.3 pmol/l) or overt hyperthyroidism (TSH<0.4 mU/l and FT4>20.1 pmol/l) during follow-up (called event). For each case, two controls were selected, matched for age and duration of follow-up; controls in study A remained TPO-Ab negative, and in study B remained without overt hyper-/hypothyroidism.

OUTCOMES: Contrast in questionnaire responses between cases and controls at baseline, at one year prior to the event and at time of event.

RESULTS: Exposure to stress was not different between subjects who developed or did not develop TPO-Ab (study A). No differences were observed in stress questionnaires between hyper-/hypothyroid cases and controls at any time point, but hypothyroid cases had less negative feelings than controls at the time of diagnosis (study B).

CONCLUSION: The data suggest that stress is not involved in the pathogenesis of AITD.