RESUMO
To investigate the prevalence of autoantibodies in a normal Thai elderly group, the authors measured anti-thyroid antibodies (anti-thyroglobulin, anti-thyroid microsome), antinuclear antibodies (ANA) and rheumatoid factors (RF) in 429 normal elderly (206 men, 223 women, age range 50-102 years). The participants recruited from Romklao Village, Lat Krabang, a suburb of Bangkok and compared to 219 young normal subjects (110 men, 109 women; age range 19-49 years). The prevalence of anti-thyroid antibodies was significantly increased in the elderly group when compared to the younger age control group (14.69% vs 5.02%, p = 0.0005). The antibody titers were found to be higher and the prevalence was more predominant in women than in men both in the elderly (21.53% vs 7.28%, p = 0.00005) and control groups (10.09% vs 0%, p = 0.0018). The prevalence of ANA in the elderly group was lower (1.17%) when compared to the control group (4.11%). ANA were characterized by low titer of antibodies and several staining patterns, and there was no difference between men and women. For RF, the prevalence was almost the same in both groups (2.79% in the elderly and 2.73% in control group) and no difference was observed. However, when all the three autoantibodies were considered, 20.28 per cent of the elderly individuals were found to have at least one of the autoantibodies which was significantly higher than in the younger control group (11.41%, p = 0.006). The prevalence was more predominant in women than in men. The results from this study can be used as basic data for the evaluation of autoantibodies testing in an elderly Thai population.