[Age-dependent changes of hypophysis-thyroid - regulation (author's transl)]

In health men and women different age total thyroxine, free thyroxine-binding-capacity, total triiodothyronine as well as TSH in serum before and after intravenous application of 500 mcg synthetic thyrothropine-releasing-hormone (TRH) were controlled. The investigations have shown: 1. With increasing age total thyroxine level in serum does not change. 2. With increasing age free thyroxine-binding-capacity in serum does not change. 3. With increasing age in men and women a significant decrease of total triiodothyronine in serum is to be measured. 4. Basal TSH serum levels do not change with increasing age. On the other hand in men and women with increasing age significant decreased TSH increments after TRH application were measured. The investigations have shown, that with increasing age the hypothalamus-hypophysial-thyroid-axis is shifting to a lower regulation level.