Relationships between insulin-like growth hormone factor-I and estradiol in reproductive aging.
OBJECTIVE
To evaluate gonadotropins, estrogen, and insulin-like growth hormone factor (IGF)-I and its binding proteins throughout the normal menstrual cycle and during aging within the reproductive life span.


METHODS
Daily blood samples were obtained from 17 normally cycling women.


METHODS
Center for Fertility and Reproductive Medicine, Newark, New Jersey.


METHODS
Ten women aged 19 to 34 years old and seven women aged 42 to 47 years old.


METHODS
Luteinizing hormone (LH), FSH, E2, and P were assayed in daily blood samples. Early follicular, late follicular, midluteal phase, and samples taken at ovulation were also assayed for IGF-I and IGFBP-I and IGFBP-III.


RESULTS
Follicle-stimulating hormone (FSH) increased significantly with reproductive aging. IGF-I and its binding proteins did not fluctuate through the menstrual cycle. IGF-I and its binding proteins did not change over the 28-year time span studied, in the face of significantly increased circulating estradiol associated with reproductive aging.


CONCLUSIONS
Rising E2 may be a subtle harbinger of the perimenopause. IGF-I and its binding proteins did not decrease with cycle stage or with aging during the reproductive years, perhaps because of increased estradiol stimulation of the somatotrophic axis.
Blake
E J
EJ
Department of Obstetrics and Gynecology, University of Medicine and Dentistry of New Jersey, Newark, USA.
Adel
T
T
Santoro
N
N
D000328:Adult; D000367:Age Factors; D000375:Aging / Q000097:blood* / Q000502:physiology; D002352:Carrier Proteins / Q000097:blood / Q000502:physiology; D004958:Estradiol / Q000097:blood* / Q000276:immunology / Q000502:physiology; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood / Q000502:physiology; D006065:Gonadotropins, Pituitary / Q000097:blood / Q000502:physiology; D006801:Humans; D007159:Immunologic Tests; D007334:Insulin-Like Growth Factor I / Q000032:analysis* / Q000276:immunology / Q000502:physiology; D008597:Menstrual Cycle / Q000097:blood* / Q000502:physiology; D008875:Middle Aged; D011374:Progesterone / Q000097:blood / Q000502:physiology; D012098:Reproduction / Q000502:physiology*
D002352:Carrier Proteins; D006065:Gonadotropins, Pituitary; D011374:Progesterone; D004958:Estradiol; D007334:Insulin-Like Growth Factor I; D005640:Follicle Stimulating Hormone