Abstract

A competitive protein-binding method was used to determine serum thyroxine concentration throughout childhood, adolescence, and in young adults. The values showed a gradual decrease as the child became older and reached adult levels by the time of adolescence. The range (mean ± 2 SD μg/100 ml) for cord serum was 8·8-14·8; for 4 weeks to 11 years, 6·5-13·9; for 11 to 17 years, 5·4-12·2, and for young adults 6·0-11·2.