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View Clinical Trial (Medical Research Study)
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Effect of Race on Gonadotropin Responses - NCT00455962-02114 (Clinical Trial 167333)
Permalink: http://www.ClinicalConnection.com/exp/ExpandedPatientViewStudy167333.aspx
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| City: |
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Boston |
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State:
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MA |
| Zip Code: |
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02114 |
| Conditions: |
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Premenopause - Healthy |
| Purpose: |
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The purpose of this study is to attempt to determine why estrogen levels are increased in
African-American women as compared to Caucasian women by evaluating estrogen feedback on the
brain. African-American women have increased bone mineral density, higher rates of twins,
greater incidence of fibroids, and increased incidence of breast cancer below 40 years of
age as compared to Caucasian women. These traits or illnesses are all believed to be
estrogen-dependent. In fact, previous research has demonstrated increased estrogen levels in
African-American women as compared to Caucasian women. However, the reason for these
differences in estrogen levels has not been studied in humans. One possibility is that
estrogen feedback on the brain differs between African-American and Caucasian women. Two
small glands in the brain (hypothalamus and pituitary) respond to estrogen. The hypothalamus
secretes GnRH (Gonadotropin-Releasing Hormone) that signals the pituitary to secrete the
reproductive hormones, LH (Luteinizing Hormone) and FSH (Follicle Stimulating Hormone).
These hormones act on the ovaries and signal the ovaries to produce estrogen and
progesterone. Estrogen in the bloodstream then acts on the brain to stop this system when
the blood has enough estrogen levels. This is called estrogen feedback. This study will
determine whether there are differences in estrogen feedback between African-American and
Caucasian women.
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| Study summary: |
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Several independent lines of evidence have suggested that reproductive endocrine dynamics
may differ between African-American (AAW) and Caucasian (CW) women. There is an increased
incidence of dizygotic twinning in African-American women and a further increase in the
incidence reported in African women compared to Caucasian, Hispanic and Asian populations.
While the etiology of dizygotic twinning is not well understood, an increase in its
incidence may imply an alteration in the integrated control of the reproductive axis which
usually favors development of a single ovulatory follicle. It is widely appreciated that the
incidence of leiomyomas is increased in African-American women. Growth factors are likely to
play a role in their control, but there is also ample evidence that leiomyomas are
responsive to gonadal steroids, decreasing in size following the menopause and in response
to hypoestrogenism caused by gonadotropin downregulation. African-American women under 40
years of age have a higher risk of breast cancer than women of all other ethnicities in that
age group, again raising the question of whether there are also differences in reproductive
hormone dynamics. Finally, bone density is increased in African-American women. In a
cross-sectional study of 54 African-American and 39 Caucasian women between the ages of 20
and 90, Perry et al found that the increase in bone density in AAW was associated with
increased serum levels of both estradiol and testosterone. Woods et al also described
increased levels of estradiol, estrone and androstenedione levels in AAW compared with
control women on a controlled low-fat, high-fiber diet. In contrast, a recent longitudinal
cohort study has suggested that AAW have lower levels of estradiol with increasing age and
BMI in comparison with CW. We have compared reproductive hormone levels in AAW and CW < 35
years old with a history of regular ovulatory cycles. Our preliminary data indicate that in
comparison to age and BMI matched CW, estradiol levels are consistently elevated across the
cycle in AAW in the absence of changes in LH, FSH, progesterone, inhibin A or inhibin B.
These relationships suggest both altered negative and forward feedback interrelationships
between FSH and LH and estradiol in the setting of normal inhibin levels. In the current
protocol we will seek to understand the mechanisms underlying these feedback differences,
which have never been addressed in these populations.
A graded infusion of estradiol and progesterone can be used to assess differences in
negative and positive feedback of gonadal steroids on LH and FSH. We have hypothesized that
differences exist in feedback regulation of the hypothalamus and pituitary as a function of
African-American or Caucasian race in reproductive aged women. |
| Criteria: |
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Premenopausal Women
- Will be non-smokers or smoke less than 10 cigarettes/day
- African-American women aged 18 to 35 years and Caucasian women aged 18 to 45 years
- BMI <30
- In good general health with normal TSH, prolactin and hemoglobin
- Normal BUN and Creatinine (< 2 times the upper limit of normal)
- On no medications for > 2 months before the study
- Regular menstrual cycles every 25 to 35 days and ovulation documented by a luteal
phase progesterone > 3 ng/ml
- With no evidence of androgen excess.
- Subjects must have no known sensitivity to any medications used in the relevant
protocol and be willing to use abstinence or barrier methods of contraception for the
duration of the study.
Subjects will be asked to volunteer information on ethnicity (self classification). Only
African-American and Caucasian subjects will be included in this aim to address the
specific hypotheses. |
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| Study is available at: |
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Massachusetts General Hospital
Boston, MA 02114
United States
Primary Contact:
Teresa Alati
Email: talati@partners.org
Phone: 617-726-8484 |
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If you are interested in this clinical trial please use the contact information above. If you would like to get additional information about this clinical trial please visit ClinicalTrials.gov.
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| Data Source: |
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ClinicalTrials.gov |
| Date Processed: |
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March 15, 2010 |
Modifications to
this listing: |
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Only selected fields are shown, please use the link
above to view all information about this clinical trial. |
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Clinical trials are medical research studies designed to test the safety and/or
effectiveness of new drugs, devices, or treatments in humans. These studies are
conducted worldwide for a range of conditions and illnesses. Learn more about
clinical research and participating in a study at
About Clinical Trials.
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