This Article Full Text (PDF) Submit a related Letter to the Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by SIMON, J. A. Articles by BUSTER, J. E. Search for Related Content PubMed PubMed Citation Articles by SIMON, J. A. Articles by BUSTER, J. E.

Variability of Midcycle Estradiol Positive Feedback: Evidence for Unique Pituitary Responses in Individual Women

J. A. SIMON^*, M. BUSTILLO, I. H. THORNEYCROFT, S. W. COHEN and J. E. BUSTER

Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology and Infertility, Harbor-UCLA Medical Center Torrance, California 90509

In women the preovulatory estradiol (E₂) level must reach a peak concentration and dose (strength and duration) to initiate the LH surge. The variability of the surge-initiating serum E₂ level in individual women from cycle to cycle, however, has not been studied. Accordingly, we studied 24 normally ovulating women longitudinally during a total of 221 menstrual cycles (range, 4–17 cycles/woman). In those women we measured periovulatory serum E₂ and LH concentrations daily from 3 days before the LH peak to the day after the LH peak. The mean peak E₂ concentration was 343 pg/mL, and the mean E₂ dose (concentration x time) was 979 pg/mL. When the values in individual women were compared between women by components of variance analysis of variance, the differences were significant (concentration, P < 0.01; dose, P < 0.005), indicating that individual women have discrete and characteristic responses to E₂ positive feedback. When E₂ peaks and doses from initial cycles were compared with subsequent cycles by regression analysis, there were strong positive correlations (peak: r = 0.47; P < 0.001; dose: r = 0.60; P < 0.001). Of the total group variance in mean E₂ peak and mean dose, 67% of the peak and 54% of the dose variance resulted from an individual woman’s cycle to cycle variability, while 33% of the peak and 46% of the dose variance was attributable to differences among the women’s responses to positive feedback.

We conclude that 1) individual women have characteristic and predictable periovulatory E2 production, leading to a LH surge which is maintained from cycle to cycle; and 2) approximately two thirds of the total variance in mean peak E₂ concentration (67%) and approximately half the variance in mean dose (54%) are the result of cycle to cycle biological variability around this characteristic periovulatory pattern of E₂ production.

^* Address all correspondence and requests for reprints to: James A. Simon, M.D., The Jones Institute for Reproductive Medicine, Department of Obstetrics and Gynecology, Eastern Virginia Medical School, 700 Olney Road, Room 2007, Norfolk, Virginia 23507.

Current address: Genetics and IVF Institute, 3020 Javier Road, Fairfax, Virginia 22031.

Current address: Department of Obstetrics and Gynecology, Tulane Medical School, New Orleans, Louisiana 70112.

Received November 22, 1985.

This article has been cited by other articles:

				J. D. Veldhuis, D. M. Keenan, J. N. Bailey, A. Adeniji, J. M. Miles, R. Paulo, M. Cosma, and C. Soares-Welch Estradiol Supplementation in Postmenopausal Women Attenuates Suppression of Pulsatile Growth Hormone Secretion by Recombinant Human Insulin-like Growth Factor Type I J. Clin. Endocrinol. Metab., November 1, 2008; 93(11): 4471 - 4478. [Abstract] [Full Text] [PDF]