THYROID-DISEASE IN THE ELDERLY .1. PREVALENCE OF UNDIAGNOSED HYPOTHYROIDISM

Background. The purpose of this study was to examine the prevalence of previously unrecognized hypothyroidism in elderly patients. Methods. The study was conducted in a primary care geriatrics clinic. Three hun dred seventy elderly patients (287 women, 83 men) between 60 and 97 ye ars of age were included in the study. Medical records of patients wer e reviewed retrospectively. Senun thyroid-stimulating hormone (TSH), f ree thyroxine (T4), height, weight, demographic variables, clinical si gns and symptoms of hypothyroidism, history of thyroid diseases and tr eatment with thyroid medications, comorbidities, and current medicatio ns were obtained from the medical records. Patients who had both eleva ted TSH levels (5.0 to 14.9 muU/mL) and normal free T4 levels (0.7 to 2.0 ng/dL) met the criteria for ''subclinical hypothyroidism.'' The cr iteria for ''overt hypothyroidism'' were TSH levels greater-than-or-eq ual-to 15 mu/mL and low free T4 levels (<0.7 ng/dL). Results. At the i nitial visit to the clinic, 18.1% of the patients (62 female and 5 mal e) had an established history of past or current thyroid disease. Anot her 20 women (5.4%) had a history of thyroid surgery. Of the remaining 283 patients with no history of thyroid disease, 14.6% of the women a nd 15.4% of the men had subclinical hypothyroidism. Overt hypothyroidi sm was discovered and subsequently treated in two female patients and one male patient (1.0% and 1.3%, respectively). Thyroid status was not significantly related to age group (60 to 64 years; 65 to 74; 75 to 8 4; 85 and older). Comorbidities typically associated with hypothyroidi sm were no more prevalent in hypothyroid patients than in cuthyroid pa tients. Conclusion. We found a high prevalence of newly diagnosed subc linical hypothyroidism in both elderly male and female patients. Thyro id status was not related to age or to coexisting diseases. The clinic al significance of treating subclinical hypothyroidism merits investig ation.