Indices of serum androgens in normal puberty: correlations of two indices with chronological age, bone age and pubertal development in boys and girls.
Two indices of free serum androgenic activity, the normalized androgen ration (NAR) and the free androgen index (FAI) were determined in 218 normal children aged 8-17.9 years. Before the onset of puberty and between chronological age 8 and 11.9 years, NAR and FAI were similar in both sexes, the NAR being less than 0.8 and FAI less than 0.1. In boys mean NAR value increased from 0.87 to 1.39 between 12.5 and 17.5 years, and mean FAI from 0.14 to 1.85 between 12.5 and 17.5 years. In girls mean NAR increased from 0.79 to 0.85 between 12.5 and 15.5 years, and mean FAI from 0.11 to 0.23, between 12.5 and 15.5 years. Both indices did not change significantly between 15.5 and 17.5 years in girls. A rapid increase in NAR and FAI occurred in boys from a mean testicular volume of 4.1 to greater than 20 ml and from genital stage G2+ to 5+. In girls a gradual increase in NAR and FAI occurred from breast stage B2+ to 5+ . Although the androgen indices increased in both sexes between pubic hair stages PH2+ and 6+, the values in girls were always less than in boys at corresponding stages suggesting an increased androgen sensitivity of the female pubic hair follicle during adolescence. The peak rise in NAR and FAI in boys between 13 and 15 years correlated closely with the timing of the pubertal growth spurt in this sex. A similar rise was not seen in girls at the time of their peak growth velocity between 11 and 13 years and suggested that androgens play only a minor or complementary part in the female growth spurt.
D000293:Adolescent; D000365:Age Determination by Skeleton; D000375:Aging; D000728:Androgens / Q000097:blood*; D002648:Child; D005260:Female; D006801:Humans; D006914:Hydroxysteroids / Q000097:blood; D008297:Male; D011627:Puberty; D012738:Sex Hormone-Binding Globulin / Q000032:analysis; D012741:Sexual Maturation
D000728:Androgens; D006914:Hydroxysteroids; D012738:Sex Hormone-Binding Globulin