Circulating thyroid autoantibodies in a sample of Italian octo-nonagenarians: relationship to age, sex, disability, and lipid profile.

Circulating thyroid autoantibodies were assessed in a sample of Italian octo-nonagenarians living in a restricted area (Val Vibrata, Abruzzo), and selected according to the absence or presence of chronic illness and disability. The study groups included: Group A ("Successful aging"), 98 free-living healthy, fully independent, octo-nonagenarians (57 males and 41 females, average age +/-SD 83.9+/-3 years); Group B ("Unsuccessful aging"), 62 highly disabled octo-nonagenarians (24 males and 38 females; average age 86.5+/-3.4 years), and Group C (Controls), 91 randomly selected healthy adult controls (42 males and 49 females; age 53.7+/-16.6 SD years, range 20-70). Serum autoantibodies to thyroglobulin (anti-Tg) and to thyroid peroxidase (anti-TPO) were measured by passive hemagglutination and radioimmunoassays (RIA); serum free thyroxine and thyrotropin by RIA. The prevalence of positive thyroid autoantibody tests was not significantly increased in the elderly groups compared to the controls, with the remarkable exception of anti-Tg detected by RIA which were increased in disabled elderly, compared to free-living elderly and controls. Two/62 disabled elderly had subclinical (1) or mild (1) primary hypothyroidism, and one free-living woman aged 90 years was hyperthyroid (toxic nodular goiter). No correlation was found between serum thyroid autoantibodies, thyroid hormones and TSH and serum lipoprotein fractions. The higher prevalence of thyroid autoantibodies found only in disabled, but not in free-living Italian octo-nonagenarians suggests that thyroid autoimmune phenomena in the elderly may be an expression of age-associated disease rather than related to the aging process in itself.