Prevalence of thyroid disease and abnormal thyroid tests in older hospitalized and ambulatory persons

To determine the utility of laboratory tests for diagnosing thyroid disease in the hospitalized elderly, we measured serum thyroid-stimulating hormone (TSH), thyroxine (T4), free thyroxine index (FT4I), triiodothyronine (T3), and free triiodothyronine index (FT3I) in 125 geriatric inpatients, mostly men, and compared the results to those in elderly ambulatory patients. Hypothyroidism (TSH greater than 10 microU/mL with a low T4 and FT4I or clinical findings) was present in 7.8% (nine of 116) of male inpatients compared to only 0.7% of male ambulatory controls (P less than 0.01). Only a few women were studied but 17% (two of 12) were hypothyroid compared to 2.4% of ambulatory elderly women. Three of the hypothyroid inpatients had no clinical clue to their hypothyroidism. Further, decreased thyroid reserve or subclinical hypothyroidism (TSH greater than 10 microU/mL with a normal T4 and FT4I and no overt clinical findings), a condition which may lead to overt hypothyroidism, was more common in male inpatients (4.3%) than in male ambulatory controls (1.8% [P less than 0.01]). Thus, a clearly elevated serum TSH (greater than 10 microU/mL) was more common in inpatient (12.1%) than in ambulatory (2.4%) elderly men (P less than 0.01). Four inpatients and nine ambulatory controls had an elevated T4 and FT4I, but in only one (0.8%) inpatient and one (0.6%) control was a final diagnosis of hyperthyroidism made; the others had no clinical findings and a normal or low T3 and FT3I.(ABSTRACT TRUNCATED AT 250 WORDS)