Assessment of Sensitivity of the Hypothalamic GnRH Pulse Generator to Estradiol and Progesterone Inhibition
Assessment of Sensitivity of the Hypothalamic GnRH Pulse Generator to Estradiol and Progesterone Inhibition
Gonadotropin-releasing hormone (GnRH) is a hormone that regulates the ability of the
 pituitary to secrete two hormones, luteinizing hormone (LH) and follicle-stimulating hormone
 (FSH). LH and FSH control the production of female hormones (such as estrogen and
 progesterone) and the development of eggs by the ovary. Progesterone and estrogen then
 decrease the number of GnRH pulses produced by the brain (and therefore the number of LH
 pulses from the pituitary). The ability to decrease GnRH pulses seems to be very important
 for normal menstrual function in adult women. The purpose of this study is to learn more
 about how GnRH and LH pulses are controlled during puberty. The information gathered in this
 study will hopefully allow us to learn more about how menstrual cycles are normally
 established in girls during puberty.
In this study, the investigators will aim to discover the effect of 7 days of estrogen and
 progesterone on GnRH pulses in girls in early and mid puberty. Ultimately, if the
 investigators understand these normal processes, the investigators may be able to better
 understand abnormalities of puberty.
Inclusion Criteria:

 -  Girls ages 8 to 14

 -  Tanner 1-3 pubertal stage

 -  Pre-menarchal

 -  Normal screening labs

 Exclusion Criteria:

 -  Abnormal screening labs

 -  Congenital adrenal hyperplasia

 -  Hyperandrogenism (e.g., hirsutism, elevated free testosterone level)

 -  Hemoglobin <12 mg/dL or hematocrit < 36% (Subjects will be offered the opportunity to
 take iron supplementation for 60 days if their hematocrit is slightly low (33-36%)
 (suggestive of iron deficiency anemia) and will then return for retesting of their
 hemoglobin/hematocrit.)

 -  Weight < 31 kg

 -  History of peanut allergy, deep venous thrombosis, breast cancer, endometrial cancer,
 or cervical cancer

 -  On hormonal medications (including oral contraceptive pills) or on medications known
 to affect the reproductive axis within 3 months of the study

 -  Pregnant or breast feeding

 -  Participation in a research study within the past 30 days that involved taking a study
 drug.

 -  Participation in a research study that involved taking up to or greater than 473 ml's
 of blood within the past 60 days.

 -  Cigarette smoking

 -  History of surgery that required bedrest within the past 30 days

 -  Family history of hypercoagulability or unexplained thromboembolic disease (not in
 setting of bedrest, surgery, or malignancy)

 -  In order to ensure an adequate number of younger girls, no more than 4 enrolled
 subjects will be Tanner stage 3