Assessment of Sensitivity of the Hypothalamic GnRH Pulse Generator to Estradiol and Progesterone Inhibition in Early Pubertal Girls (JCM026)

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