THYROID AUTOANTIBODIES IN HOSPITALIZED CHRONIC GERIATRIC-PATIENTS - PREVALENCE, EFFECTS OF AGE, NONTHYROIDAL CLINICAL STATE, AND THYROID-FUNCTION

OBJECTIVE: To investigate the effect of age, clinical condition, and t hyroid function on the prevalence of thyroid autoantibody positivity i n hospitalized chronic geriatric patients. DESIGN: A screening study o f hospitalized chronic geriatric patients. PARTICIPANTS: 249 non-selec ted, hospitalized, chronic geriatric patients more than 60 years of ag e and 81 20 to 40-year-old healthy persons. MEASUREMENTS: Thyrotropin (TSH); thyroxine (T-4) and free thyroxine (FT4); and triiodothyronine (T-3), thyroglobulin (Tg), antibodies against thyroid peroxidase (AbTP O) and antibodies against thyroglobulin (AbTg) estimation in a screeni ng study. RESULTS: AbTPO positivity (AbTPO+) was found more often than AbTg positivity (AbTg+) (15.3% vs 9.2%, P = .04), one being positive (Ab+) in 19.3%. The occurrence was higher in females than males (Ab+:2 7.1% vs 7.1%, P < .001; AbTPO+:21.9% vs 5.1%, P < .001; AbTg+:13.2% vs 3.1%, P = .0052). Among the Ab+ patients, AbTPO was more often positi ve than AbTg (40/48 vs 21/48, P (.001). The sensitivity, specificity, and positive predictive value of Ab positivity to detect a thyroid dis order were 0.35, 0.85 and 0.38, respectively. Within the population of euthyroid geriatric patients, the occurrence of AbTg+ (chi((2)(2)) = 8.65, P = .013) and Ab+ (chi((2)(2)) = 8.02, P = .018) correlated posi tively with the age of the patients, and there was also a female predo minance (AbTPO+ 18% vs 3.7% in the males; AbTg+ 13% vs 2.4%; Ab+ 25.8% vs 6.1%). When compared with 20 to 40-year-old subjects, only the eut hyroid greater than or equal to 80-year-old patients showed a signific antly higher occurrence of Ab+ (26.2% vs 9.9% chi((1)(2)) = 5.64, P = .017). In the euthyroid greater than or equal to 80-year-old females, AbTPO+ was 25%, AbTg:22.2%, and Ab+: 36.1%!. The nonthyroidal clinical state of the euthyroid patients did not correlate with the antibody p revalence. CONCLUSIONS: In hospitalized chronic geriatric patients, Ab Tg and especially AbTPO positivity is frequent, even in euthyroid pati ents without goiter. This aspecific Ab positivity in the euthyroid sta te correlates to the age, but not to the severity of the nonthyroidal clinical condition of the patients and explains why the Ab positivity is not predictive enough for thyroid dysfunction in this subpopulation . Thus, in hospitalized chronic geriatric patients the AbTg and AbTPO titers should be examined only in cases where thyroid screening (TSH) reveals abnormal results.