Prevalence of thyroid autoantibodies in ambulatory elderly women.

Major improvements in thyroid autoantibody testing have now become widely available. Seventy-five elderly ambulatory women from a senior citizens' center (mean age 74.5 yrs) were studied to reassess the prevalence of thyroid autoantibodies and to demonstrate how such tests related to clinical signs and symptoms of thyroid disease. We used the enzyme-linked immunoassay (ELISA) technique for the measurement of autoantibodies to thyroglobulin (hTg) and thyroid peroxidase (hTPO) (as microsomal antigen), since ELISA systems are economical, highly sensitive and specific for population screening. Autoantibodies to hTPO (hTPO-Ab) were present in 44% and hTg autoantibodies (hTg-Ab) in 32% of the study group. Ten women (13.3%) had elevated thyrotropin (TSH) levels. An elevated serum TSH was associated with the presence of hTPO-Ab in varying concentrations. The mean TSH value of 7.2 microIU/mL in those women with hTPO-Ab was significantly higher than the mean of 4.7 microIU/mL found in those women without thyroid autoantibodies (p < 0.01). However, additional testing for hTg-Ab was of little clinical value. These data indicate the high prevalence of thyroid autoimmune disease in the elderly female population. We conclude that screening for thyroid dysfunction is best achieved by the measurement of serum TSH in all women over the age of 60 years. The measurement of hTPO-Ab, but not hTg-Ab, was helpful in confirming the cause of thyroid failure in the elderly female population.