Serum T4, T3 and TBG concentrations during puberty in males

Measurements of serum thyroxine (T4), thyroxine binding globulin (TBG), and triiodothyronine (T3), using RIA, were conducted in healthy Israeli boys, 149 children from the age 8 years were divided into five groups according to Tanner's puberty stages. The correlation with Tanner's staging showed a significant decrease in T4 and TBG concentrations during puberty. However, T3 decreased only toward the last stage of puberty (between P4 to P5). Our data indicate that during puberty in male subjects the decrease in TBG plays a significant role in the decrease of thyroid hormone concentrations.