Thyroid Function Tests in Elderly Hyperthyroid Patients

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Abstract
Several tests of thyroid function were performed in 35 hyperthyroid patients over the age of 65 (elderly). The results were compared to those of similar tests in 48 hyperthyroid patients under the age of 65 (young). Total serum thyroxine (T4) was within the normal range in 14% of the elderly and 11% of the young hyperthyroid patients. The free thyroxine index (FTI) was within the normal range in 11% of both groups. The triiodothyronine uptake (T3U) proved to be a poor test in both groups. Although elevation of the T3 level allowed a diagnosis of T3-toxicosis in 2 elderly and 3 young hyperthyroid patients, the T3 level was normal in 34% of the elderly and 13% of the young subjects. Correction of the T3 range for age reduced the number of normal T3 values to 12.5% in the elderly hyperthyroid patients. The 24 h uptake of radioactive I was normal in 12% of the young hyperthyroid patients, 27% of the elderly patients with Graves'' disease and 70% of the elderly patients with toxic nodular goiter, despite recent readjustment of the normal range for the test. The diagnosis of hyperthyroidism in the elderly may be difficult and no single test can be relied upon to exclude the diagnosis.