THYROID AUTOIMMUNITY AND AGING

Ageing is associated with the appearance of several serum autoantibodi es, including thyroid autoantibodies. The biological and clinical sign ificance of this phenomenon is still unknown, since, with the exceptio n of primary myxedema, the prevalence of clinically overt thyroid auto immune diseases is not increased in the elderly. The peculiar link bet ween autoimmune thyroid failure and ageing is also underscored by the high prevalence of subclinical hypothyroidism in elderly subjects with positive serum thyroid autoantibodies, and could be the consequence o f preferential age-dependent expression of destructive effector mechan isms and/or increased target gland susceptibility. Thyroid autoimmunit y and subclinical hypothyroidism have also been implicated in the path ogenesis of other age-associated disorders, in particular coronary hea rt disease. Interestingly, recent data from our laboratories showed th at thyroid autoantibodies are rare in healthy centenarians and in othe r highly selected aged populations, while they are frequently observed in unselected or hospitalized elderly. Taken together, these data sug gest that thyroid autoimmune phenomena are not the consequence of the ageing process itself, but rather might be related to age-associated d isease.