Thyroid dysfunction in elderly hospitalized patients. Effect of age and severity of illness.

To investigate the relative effects of aging and severity of illness on thyroid function as well as the prevalence of thyroid dysfunction in the elderly, we performed thyroid function testing on 190 hospitalized patients 60 years of age or older. Abnormalities of thyroid test results were frequent, and only 27% of patients had normal values for all thyroid function studies. The largest number of patients (125) had a low serum T3 level. Regression analysis showed that severity of illness was a stronger predictor of the T3 level than was age. Our results confirm previous observations that clinical thyroid disease in the hospitalized elderly is not uncommon and often goes unrecognized. Our results also demonstrate for the first time that low concentrations of T3 correlate with a quantitative measure of the severity of illness but only marginally with aging.