Urinary testosterone glucuronide and sulphate in newborns and young infants

Urinary testosterone glucuronide and sulphate was determined separately by gas chromatography in 39 newborns and young infants (34 males and 5 females). In all cases, testosterone sulphate was higher than glucuronide. Boys excreted more of both conjugates (sulphate 6.7, glucuronide 2.2 mug/24 h) than girls (1.1 and 0.7 mug/24 h, respectively). Boys older than 3 weeks had higher values than boys younger than 2 weeks. The levels correlated positively with chronological age, negatively with the gestational age and not at all with the bilirubin levels. It is concluded that testosterone is excreted preferentially as the sulphate in the newborn period and that the high sulphokinase activity in foetal and neonatal testes is more likely responsible for this phenomenon than an impaired glucuronizing capacity of the liver.