[Age and thyroid function (radioimmunologic study)]

Radio-immunologic study on the hormones of hypopheseal-thyroid axis was performed in 207 healthy subjects, aged from 0 to 79, namely: thyroxine (T4), triiodothyronine(T3) revrese T3 (rT3), thyrotropic hormone (TTH), thyroxine-binding globulin (TBG) and the index of free thyroxine was calculated (IFT4). Considerably elevated levels of thyroid indices were established at birth and only rT3 and TTH were normalized during the early neonatal period. The thyroid indices were also kept higher during the period of childhood and adolescence as compared with the mature and old age. A tendency was observed to a constant decrease of the levels of T3 and TBG with age advancing.