Some sex hormone profiles are consistent over time in normal menstruating women: implications for sports injury epidemiology.
OBJECTIVE
It is unclear whether sex hormone profiles obtained in two consecutive months are consistent within women. Month-to-month consistency in daily, nadir, peak and mean hormone concentrations during the early follicular and luteal phases in recreationally active, young eumenorrheic women was prospectively examined.


METHODS
60 healthy, non-smoking women who reported normal and consistent menstrual cycles lasting 26-32 days for the past 6 months were followed prospectively to obtain serum samples for the first 6 days of menses and for 8 days after a positive ovulation test over two consecutive months. Month-to-month consistency of daily concentrations of oestradiol (pg/ml), progesterone (ng/ml), testosterone (ng/dl), sex hormone-binding globulin (nmol/l) and free androgen index were determined using linear mixed models. Month-to-month consistency in nadir, peak and mean concentrations were then assessed using intraclass correlation coefficients and SEM to more precisely examine intraindividual consistency.


RESULTS
Linear mixed models revealed stable hormone concentrations across cycles and cycles by day. Reliability estimates for nadir, peak, mean menses and mean postovulatory concentrations range from 0.56 to 0.86 for oestradiol, 0.44 to 0.91 for progesterone, 0.60 to 0.86 for testosterone, 0.88 to 0.97 for sex hormone-binding globulin and 0.78 to 0.91 for free androgen index.


CONCLUSIONS
Hormone profiles were reproducible over two consecutive months. To reduce month-to-month intraindividual variations and improve measurement consistency, it is recommended that multiple samples be taken over consecutive days as opposed to a single sample.
School of Health and Human Performance, University of North Carolina at Greensboro, USA. sjshultz@uncg.edu
S J
SJ
Shultz
L
L
Wideman
M M
MM
Montgomery
B J
BJ
Levine
D000728:Androgens / Q000378:metabolism*; D001265:Athletic Injuries / Q000175:diagnosis / Q000209:etiology*; D004958:Estradiol / Q000378:metabolism; D005260:Female; D005498:Follicular Phase / Q000378:metabolism; D012739:Gonadal Steroid Hormones / Q000378:metabolism*; D006801:Humans; D008183:Luteal Phase / Q000378:metabolism; D008597:Menstrual Cycle / Q000378:metabolism*; D011374:Progesterone / Q000378:metabolism; D011446:Prospective Studies; D015203:Reproducibility of Results; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism*; D013739:Testosterone / Q000378:metabolism; D055815:Young Adult
D000728:Androgens; D012739:Gonadal Steroid Hormones; D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D011374:Progesterone; D004958:Estradiol