Plasma Testosterone-Binding Affinity and Testosterone in Umbilical Cord Plasma, Late Pregnancy, Prepubertal Children, and Adults

The plasma concentration of testosterone, measured by a competitive protein binding radioassay, and the plasma testosteronebinding affinity (TBA) were determined in male and female prepubertal children, adult males and females, females on oral contraceptives, pregnant females at term, and in umbilical cord blood. The TBA expressed as 1/S (an arbitrary unit: the reciprocal of the quantity of plasma needed to bind 50% of the 3H-testosterone tracer) of umbilical vein plasma was 19±5 (sd), 3-day-old infants 54±17 (sd), adult males 61±21 (sd), adult females 90±18.5 (sd), prepubertal males 110±13 (sd), prepubertal females 133±22 (sd), females on oral contraceptives 153±21 (sd), and pregnant females at term 212±37 (sd). All values differed significantly, with the exception of the comparison between 3-day-old infants and adult males and between adult females on oral contraceptives and prepubertal females. The plasma testosterone concentration of umbilical vein blood was 56 ng/100 ml ±15 (sd), of adult females 45.4±17.7 (sd), of females on oral contraceptives 67±6.5 (sd), of pregnant females at term 140±41 (sd), and of adult males 625±104 (sd). The values in prepubertal females ranged from <10 to 48 ng/100 ml, with a median of 21 ng/100 ml, and in prepubertal males from <10 to 75 ng/100 ml, with a median of 18 ng/100 ml; no sex difference was found. A correlation was shown between plasma TBA and concentration of plasma testosterone in adult females and males. The umbilical artery and umbilical vein plasma testosterone concentrations were measured in 5 paired specimens. In 3, the arterial concentration was elevated and in 2 the arterial concentration was the same as the vein. The mean arterial and venous concentrations did not differ significantly.