Prevalence of thyroid dysfunction in adults over age 60 years from an urban community

Thyroid dysfunction affects a considerable portion of the elder population. The aim of the present study has been to assess the prevalence of thyroid dysfunction in adult healthy subjects over age 60 years from our population. We performed a descriptive, cross-sectional study in the setting of a sanitary area in an urban community in Madrid (Spain). Serum concentrations of thyrotropin (TSH) and free thyroxine (FT4) were determined by an electrochemiluminescency assay in all participants after antecubital venous sampling. A second examination, including the measurement of triiodothyronine and thyroid autoantibodies, was performed in subjects with abnormal results. A total of 127 women and 167 men, aged 60 to 84 years, were studied. We identified 6 subjects (all women) with hypothyroidism (2.04%) and 19 (6 women, 13 men) with hyperthyroidism (6.46%, 95%CI 3.65-9.27%). There were 3 cases (1.02%) of subclinical and 3 cases (1.02%) of overt hypothyroidism. In the hyperthyroid group only one patient (0.34%) showed overt hyperthyroidism. TSH test did not detect erroneously any case of hypothyroidism or hyperthyroidism, although one patient with hyperthyroidism was not diagnosed by this test. FT4 test detected erroneously two cases of hypothyroidism; however, it was the only way to detect the patient with overt hyperthyroidism. In conclusion, in our population over age 60 years the prevalence of hypothyroidism was 2.04% and that of hyperthyroidism 6.46% (95%CI 3.65-9.27%). The total prevalence of thyroid dysfunction was, therefore, 8.50% (95%CI 5.31-11.69). Our data suggest that TSH test is probably enough to screen for thyroid dysfunction in adults over age 60 years.