抄録
Functional changes of the pituitary thyroid system in healthy aged subjects ranging from 60 to 94 year olds were compared with those of healthy adults from 25 to 35 year olds.
As a result, significant decreases in triiodothyronine resin sponge uptake rate and free thyroxine index (FT4I) were observed in the aged group, while no significant change in the thyroxine levels was indicated. TSH levels in serum tended to be elevated in the aged, although no negative correlation between TSH levels and FT4I was seen. A significant difference in TSH responses between 100μg and 300μg doses of TRF was observed in the adult control, on the other hand, no difference was seen in the aged group. A comparison of TSH responses to relatively small doses of TRF (100μg) was made between the adult control and the aged, and a significantly higher responsiveness was observed in the aged group. It is postulated that a higher TSH response to relatively smaller doses of TRF is characteristic in the aged probably due to a reflection of a latent hypothyroid state.
