| Abstrakt: |
Extract: Data are provided which concern daytime levels of circulating follicle-stimulating hormone (FSH), luteinizing hormone (LH), and estradiol and progesterone in healthy female children and adolescents. These findings are correlated with sexual and skeletal maturation. Serum estradiol and testosterone levels were low in childhood, but rose to adult levels coincident with the appearance of secondary sexual characteristics. Serum LH levels did not rise above prepubertal levels until these characteristics were already apparent. Serum FSH levels showed a biphasic pattern with age; widely scattered values, some into the adult range, were seen in infancy. Mean FSH levels then declined throughout childhood until the onset of clinical puberty at which time they increased again to adult levels. Serum progesterone concentrations remained low (below 150 ng/100 ml) until menarche. Levels of serum progresterone which suggested possible ovulation and corpus luteum formation (over 200 ng/100 ml) were found in 9 of 30 girls who were less than 3 years postmenarchal.Speculation: The finding of high serum FSH levels in female, but not in male, infants suggests that the infantile ovary may be relatively resistant to FSH stimulation. The decline in FSH levels during early childhood may represent increasing ovarian maturation, at least in terms of ability to secrete as yet unidentified gonadotropin-inhibiting feedback substance (or substances). The onset of female puberty appears to be heralded by increasing FSH secretion; although nocturnal LH release may be characteristic of early puberty, daytime elevation of this hormone is not seen until midpuberty. The surprising finding of luteal range serum progesterone levels in many early postmenarchal girls suggests that anovulatory cycles may not be characteristic of these years. The reported relative infertility of adolescent girls may relate to factors other than ovulation (such as a short corpus luteum life-span, defects in sperm capacitation, or impaired blastocyst implantation). |
